Corundum gemstone and its properties. Natural and synthetic corundum
Looking at transparent corundum, fiery red ruby and blue sapphire, few of us can imagine that these stones, so different in appearance, have something in common. Meanwhile, all the above-mentioned minerals are very similar in their physical and chemical properties.
In essence, they differ only in the presence of various impurities, thanks to which the stones acquire one color or another. Pure corundum is colorless, chromium oxide gives the stone all shades of red, titanium can color the mineral blue, and iron oxide gives the crystals a yellow tint.
However, in ancient times, when it was not possible to conduct a deep analysis of the composition of minerals, the classification of stones was carried out according to the principle of external similarity. For example, the word “corundum” was used to describe extremely hard stones, second only to diamond, imported from India.
Sapphires (from the Greek "sappheiros", which in turn came from the Hebrew "sappir" - "blue") most often called lapis lazuli and other opaque blue minerals. The word "ruby" (from the Latin "rubens" - "red") appeared only 300 years BC. Before that, all red, luminous stones (red garnets, rubies, spinels) were called carbuncles in the countries of medieval Europe and yakhonts in Rus'.
It was the ruby, sparkling in the dark like a hot coal, that in ancient times was valued higher than diamond. In the Roman Empire, this stone was dedicated to the god of war Ares and the titan Kronos; in India, China, Burma, Japan it was considered a symbol of vitality, love, passion, as well as royal dignity.
Sailors always took it with them on voyages, as there was an opinion that this stone could prevent shipwrecks. In India, rubies, called "ratnaraj" (translated from Sanskrit - "king of precious stones"), or "ratnanayaka" ("leader of precious stones") were divided into four castes (like the whole society).
Depending on one's caste, the stone had a different effect on the person who possessed it. The brahman ruby contributed to the awakening of spiritual energy, the kshatriya helped to gain power over people and bestowed invincibility in battle, the vaishya could ensure good luck in trade, and the shudra was only suitable for making jewelry.
The magicians of Burma believed that a ruby sewn under the skin would make a person completely invulnerable to arrows, swords, spears and bullets. In addition, it was believed that by changing its color this stone could warn the owner of danger. At the same time, in order to best manifest the magical properties of the crystal, it should be worn in the form of a pendant at the level of the heart, and so that the stone is in constant contact with the body.
What is it really like, this mysterious stone, so varied in color and magical properties attributed to it? We will try to find the answer to this question, while making efforts to debunk the most persistent myths and misconceptions about corundum and its varieties.
Ruby and sapphire have nothing in common. In fact, both of these stones are a type of corundum - a mineral second only to diamond in hardness, and rightfully, on a par with diamond, emerald and pearl, firmly holding a leading position in the world of jewelry.
Sapphire can only be blue. Jewelers use the word "sapphire" to describe all varieties of corundum, with the exception of red ruby. Sapphire can be white, yellow, green, pink, black. To designate the pink-red with a yellowish tint of precious material mined in Ceylon, the word “padmaradshah” or “padmaradsha” (from the Sinhalese padmaragaya - lotus color) is used.
In ancient times, colored varieties of corundum (now most often classified as sapphires) were called differently. For example, yellow stones were called “oriental topazes”, yellowish-green - “oriental chrysolites”, green - “oriental emeralds”, bluish-green - “oriental aquamarines”, violet - “oriental amethysts”, pink - “oriental hyacinths”.
Corundums are used only for making jewelry. A completely wrong opinion. Opaque stones, crushed into powder and used as an abrasive, are referred to in the trade as "corundum". In addition, the well-known “emery” is also powdered corundum mixed with magnetite and other heavy minerals. "Diamond spar" - crushed dull corundum from India - is used for grinding. In addition, bearings for moving parts in high-precision instruments and watches are made from corundum. But in this area, synthetic stones are most often used. And finally, since 1960, various industries (from medicine to space research) have used a ruby laser, the rays of which can easily burn through sheet material, drill a hole in hard alloys, etc.
The color of corundums is uniform. Most often this is not the case. Upon closer examination, you will notice that, for example, purple stones consist of alternating blue and red layers. Yellow-blue spotted stones are often found, and some asteria (star stones), due to the peculiarities of the crystal structure, cut in the form of cabochons, under appropriate lighting give a bright light six-rayed star. The most common types of stones found are blue (star sapphire) and red (star ruby).
Sapphire is a blue variety of corundum. Indeed, most often the mentioned term is used in precisely this meaning. But sometimes it can be attached to other minerals. For example, blue tourmaline is sometimes called “Brazilian sapphire”, and cordierite is sometimes called “water sapphire” or “lynx sapphire”.
Sapphires and rubies are not used to make large jewelry. This is true. Most often, the above-mentioned stones are used as inserts in rings and earrings, since rubies and sapphires are quite expensive, and they cannot boast of large sizes. But there are still exceptions.
Large sapphires are more common than rubies. For example, the Smithsonian Institution houses the Black Star of Queensland star sapphire (733 carats). Two more large star sapphires can be seen at the New York Museum of Natural History: the Star of India (blue, 536 carats) and the Midnight Star (black, 116 carats). Busts of American presidents (A. Lincoln (2302 carats), J. Washington (1997 carats) and D. Eisenhower (2097 carats)) installed in the Washington Museum are made from sapphire crystals. The Diamond Fund of Russia houses a sapphire weighing 258.18 carats.
Large rubies, as mentioned above, are extremely rare and therefore usually very expensive. The Burma Museum in London currently houses an untreated Burmese ruby (3450 carats), an even larger crystal (of low jewelry quality) 14 cm high and weighing 8500 carats, processed in the shape of the Liberty Bell. The most famous asteria (star rubies) in India are “Rajarathna” with a six-pointed star (2475 carats) and “Niilanjahi” with a twelve-pointed star (1370 carats).
The fluorescence effect is characteristic only of natural rubies. Wrong opinion. A fluorescent doublet located in the red region of the visible spectrum, caused by both sunlight and ultraviolet rays, is observed in both natural and synthetic rubies.
Carbuncle is a synonym for ruby. In ancient times, “carbuncles” were most often called blood-red, with a fiery reflection, pyropes (a type of garnet). However, the same term was used to refer to red spinel (which, like pyropes, was sometimes confused with ruby) and, in fact, rubies.
The darker the ruby or sapphire, the more valuable it is. A colored gemstone should be neither excessively light nor extremely dark. The most expensive are considered to be a pigeon's blood ruby and a cornflower blue sapphire. The presence of a gray or brown tint can significantly reduce the price of a stone.
If a gemstone has no visible inclusions, it means it is artificial. Indeed, most gemstones have minor inclusions of other minerals inside (the number of such inclusions determines the price of the stone). Perfect stones of absolute purity are extremely rare. The cost of such crystals is very high. In addition, it should be remembered that a good gemstone should not have inclusions visible to the naked eye.
Natural untreated corundum stone is unremarkable. But the jeweler-cutter turns it into delightful colored stones. The most desirable corundums are ruby and sapphire.
What is corundum
Corundum is aluminum oxide, a crystalline form of alumina. Hardness on the Mohs scale is 9 (only diamond has a higher hardness).
The shape of the crystals resembles a barrel, double pyramid or flat-table. In the rock these are individual inclusions or grains, dense granular conglomerates, fine-grained massifs.
| Formula | Al2O3 |
| Molecular mass | 101,96 |
| Color | Blue, red, yellow, brown, gray, pink |
| Stroke color | Absent |
| Shine | Glass, frosted |
| Transparency | Transparent, opaque |
| Hardness | 9 |
| Fragility | Fragile |
| Cleavage | No |
| Kink | Uneven |
| Density | 3.9-4.1 g/cm³ |
| Melting temperature | 2050 °C |
| Point group | 3m (3 2/m) |
| Space group | R3c (R3 2/c) |
| singonia | Trigonal |
| Number of formula units (Z) | 6 |
| Optical type | Anisotropic |
| Refractive index | nα=1.767 - 1.772 nβ=1.759 - 1.763 |
| Birefringence | Low, primarily gray and white |
| Optical relief | High |
| Color in reflected light | Colorless |
| Optical axis dispersion | strong |
| Pleochroism | Invisible |
Specimens with minimal impurities are transparent and of increased hardness. But colorless corundums are rare.
Most often, crystals contain impurities that determine their color:
- iron – brown scale;
- iron oxide plus nickel – yellow;
- iron plus manganese – pink;
- titanium – blue;
- chrome – red.
That is, rubies are obtained thanks to chromium, sapphires are created by titanium.
To make the color thicker, the stones are irradiated with x-rays. Heat creates delicate shades: for example, a dark brown gem will turn beige.
For centuries, people have considered ruby and sapphire to be different stones. Only modern science has established that both of them are corundum.
Symbolism of the stone
The history of corundum goes back thousands of years. It has always been an attribute of power: the priests of Ancient Egypt and the high priests of Judea decorated their robes with sapphires.
Since the Middle Ages, corundum has been known in Russia. A little later they were brought to Europe from India by merchants.
The established meaning of the scarlet stone is chosenness, power, greatness. The “Black Prince” ruby adorns the crown of British monarchs, and four stones adorn the cap of Monomakh.
Jewelry with a ruby or a cut stone is a status gift to the top officials of a state or business empire.
History with the name
It is believed that the term “corundum” goes back to Sanskrit (the proto-language of India) and means “ruby”.
The old names of minerals are associated with the East:
- “Oriental amethysts” – purple stones;
- “oriental emeralds” – chlorosapphires;
- “Oriental diamonds” are impeccably transparent leucosapphires.
In Rus', corundums were called yakhonts: sapphire – azure, ruby – scarlet.
Where are the stones mined?
Most corundum is mined in the “Asian quadrangle” - India, Myanmar, Sri Lanka, Thailand (formerly Siam).
The world's proven reserve of rubies is twenty times less than that of sapphire.
The world's best rubies come from Mogok (Myanmar, former Burma) and Sri Lanka; premium sapphires come from Indian Kashmir.
There are other mining sites. Australia and African Tanzania are sources of rare green and black sapphires.
In America, Canada and the USA have stones. Europe is represented by Norway, Turkey, Greece.
In Russia, corundum is mined in the polar Urals, Krasnoyarsk and Primorsky territories.
The newest deposit of stones is from Kazakhstan.
Types of corundum
The most valuable types of stone are ruby and sapphire. They exist in several variations.
Sapphires
The range of shades ranges from bright cornflower blue to slightly bluish.
Colored sapphires are called fancy:
- padparadscha - rich orange, yellow or tea rose shade; in India this is the name of the lotus flower; stones can be light or darker, of varying transparency;
- violet – rich violet;
- chlorosapphire – green; the best specimens are sometimes indistinguishable from emerald;
- Leucosapphire is a colorless (white) stone of impeccable transparency.
It's just that only blue stone is called sapphire. For others, the description specifies the color (yellow, green, others).
Rubies
The color range of the stone ranges from light pinkish to deep purple. Main types of rubies:
- Ceylonese. Rich purple or lilac.
- Siamese. Spectacular purple, reddish-brown specimens.
Owning any ruby item means status for a person, belonging to the elite.
Ruby Among rubies and sapphires, sometimes you come across specimens with a “star,” usually six-rayed. This is a “star-shaped” or with an asterism effect, a type of stone.
Other types
Simpler specimens are opaque, cloudy, dark:
- common corundum – opaque gray, with crystals on the surface;
- emery – gray-black interspersed with magnetite and hematite.
Collectors welcome large, well-formed corundum crystals of any degree of transparency.
Pink corundum
The first artificial corundums were produced a century and a half ago.
Today, synthetic corundum is grown on an industrial scale in the USA, Germany, Switzerland and Russia.
The result surpasses the natural original in all respects: strength, beauty, functionality.
The stones are used for industrial needs and for the beauty industry. Almost all jewelry and decorative accessories in the publicly available ruby and sapphire segment are made with artificial corundum. Self-respecting manufacturers do not hide this, indicating on the tag the origin of the product’s inserts.
Ring with synthetic corundum Jewelry value
Varieties of corundum: sapphire and ruby – first-level precious stones:
- The richer the shades of rubies, the more valuable they are.
- Unlike red minerals, the best sapphires are those of medium color saturation, but with a depth of shades.
- A colorless, clear, brightly shiny stone that looks like a diamond, so it is also highly valued.
- The cheapest corundums are brown.
Transparent, rich tones of corundum are often more expensive than their diamond counterparts.
Areas of use of corundum
Depending on the physical and aesthetic conditions of corundum, the scope of application of the raw material is different.
Jewelry
In jewelry, the best examples of natural or synthetic materials are in demand. Gems are inserted into earrings, pendants, rings, brooches, and bracelets.
Ring with corundum Men's segment - rings, cufflinks, tie clips.
The publicly available assortment of jewelry stores is synthetic corundum in 925° silver or 585° gold. Elite - real in high-carat gold or platinum.
The cost of budget accessories is thousands of rubles. Prices in the premium segment are tens of thousands.
Artificial corundums are valued at 100–700 rubles.
Before and after treatment Other areas
Durable artificial raw materials, rejected by jewelers, are used by industry:
- abrasive material in grinding machines; sometimes it’s just a whetstone or regular sandpaper;
- products from the radio electronics and precision engineering industries (lasers, drilling rig parts, medical instruments);
- glass in rockets, airplanes, mobile gadgets - synthetic sapphire;
- parts of luxury wristwatch mechanisms;
- thermal insulation (a millimeter corundum layer is similar to 50 mm of mineral wool);
- grinding paste.
In the era of vinyl records, “eternal” styli for turntables were made from corundum.
How to wear jewelry
Externally, artificial and natural inserts of accessories are indistinguishable, so the wearing rules are similar:
- corundum is combined with gems of equal level: jewelry with malachite, turquoise, jasper, coral or other similar ones - bad manners;
- the younger the owner, the lighter and smaller the inserts; pink or sky blue is suitable for a teenage girl or young girl; regal purple and deep blue - for a mature lady;
- if you want to show off a stone, choose a modest frame, preferably silver;
- appropriate wardrobe: branded or custom-made.
Colorful colors, a tracksuit or cheap fabric will blur the impression of the decoration.
Rules for caring for corundums
Caring for durable stones is easy:
- jewelry is regularly wiped with a damp cloth;
- clean with a weak solution of ammonia (10–15 drops per glass of water) or mild washing powder (a teaspoon per glass);
- stored in a box with other jewelry.
You need to make sure that the insert stone sits firmly in the frame and does not fall out. It is undesirable to heat it too much: it will fade.
Caring for synthetic corundum is even simpler: temperatures, sun, and household chemicals do not matter.
How to identify a fake
Instead of natural corundum, the following types of imitations are offered:
- synthetic stone;
- refined crystals;
- glass.
To distinguish a fake, different methods are used.
Decoration with crystal Synthetics
It is impossible to distinguish from the original externally. Ultraviolet light, a microscope or a magnifying glass will help determine the origin of the stone:
- Natural publicly available specimens always have inclusions and defects (microcracks and air bubbles). Flawless natural ones can only be bought at auctions.
- Synthetics are structurally and color ideal. But under a microscope, curvilinear zoning is visible: traces of crystal growth.
- When growing sapphires, titanium is added, which leaves a yellowish-green trace in the crystal. If a pebble turns green when exposed to ultraviolet light, it is definitely artificial.
A reliable marker is the price. Real corundum of jewelry grade is never cheap.
Ennoblement
To raise the price, natural faded or very light specimens are “ennobled” by heat treatment or irradiation. You can only check the first method. When reheated, the colored stone will lighten.
Glass
The standard way for minerals to identify such a fake is to hold the sample in your hands. If it heats up quickly, it's glass.
Magic of stone
Corundum is suitable for strong-willed, purposeful individuals. Or those who strive to become one.
The magic of the stone activates internal reserves, calms the boiling passions, and helps to implement projects.
Talisman jewelry
For specific purposes, the type of jewelry with stones matters:
- Earrings. They “force” the hostess to think about the meaning of life, to honestly evaluate her character and actions. Especially useful for those who want to achieve harmony with themselves and the Universe. It is believed that such accessories whisper the right decision to the owner if she mentally asks the stone for it.
- Ring. Constant wearing reveals dormant talents and abilities in the owner. Helps to reach spiritual heights.
A ring or ring is worn as a talisman on the right middle finger.
- Pendant, pendant, brooch. They benefit overly emotional people: they help overcome attacks of rage, an aggressive or restless mood.
- Necklace, beads, bracelet. They bring peace of mind and drive away confusion of feelings.
Jewel Gems stimulate mental activity, strengthen memory, and increase the desire for education.
Esotericists insist: the main purpose of corundum is to stir up a person, awaken personal potential and concentrate it on the main thing.
A kind of mutual exchange occurs: a person gets ready to do something, and the stone helps him.
Stone color
Magical properties are also determined by the color of the talisman insert:
- red stone attracts positive energy, creating a protective “cocoon” around the owner; it is a symbol of passionate love;
- blue is worn as a symbol of fidelity;
- green uplifts the mood;
- The mission of the colorless stone is to help the owner develop willpower, confidently move towards the goal and achieve success.
The best talismans are a ring, a ring or a pendant. Or a pristine, unprocessed pebble, which is carried with you without advertising it.
Therapeutic effect
Healers consider the healing properties of a stone to be equally effective in a pocket, jewelry or on a cord.
The nature of the effect is determined by the color of the mineral:
- Violet. Calms nerves, anxiety, and drives away depression. Useful for people with mood swings. It is recommended to wear it for traumatic brain injuries, vascular diseases, and neuralgia.
- Red. Normalizes metabolism and hormonal levels, improves blood quality, heals the heart and blood vessels. Activates the endocrine system.
- Blue. Has the ability to preserve and restore eye health.
- Green. Improves digestion, protects against colds or eases their course.
- Orange, yellow. They create a rejuvenating effect, restore metabolic processes, and improve the functioning of the gastrointestinal tract.
Decoration with natural stones of different colors has a complex effect, but not as strong as a single crystal.
Corundum and Zodiac
Corundums by zodiac sign are suitable for almost everyone:
- Ruby is destined for Aries if they are over forty years old;
- ideal for the zodiac signs Pisces, Cancer and Aquarius - blue sapphire;
- According to the horoscope, it is better for Taurus to carry corundum in a bag along with turquoise;
- For Leos, a pair of “corundum plus amber” or “corundum plus brownish agate” is suitable;
- Capricorn has good energy compatibility with ruby.
| Zodiac sign | Compatibility |
|---|---|
| Aries | – |
| Taurus | + |
| Twins | + |
| Cancer | +++ |
| a lion | + |
| Virgo | + |
| Scales | + |
| Scorpion | + |
| Sagittarius | + |
| Capricorn | + |
| Aquarius | + |
| Fish | + |
(“+++” - fits perfectly, “+” - can be worn, “-” - is strictly contraindicated).
If you like the stone, but astrology is against it, an artificial analogue will do. Outwardly indistinguishable from the original, but devoid of magical properties.
Conclusion
Precious corundums delight the eye, raise self-esteem, make you believe in yourself and achieve unattainable goals.
Artificial stones are no worse: they look like real ones, but are financially accessible to almost everyone. Decorations with them will make the hostess stand out from the general background.
In this article:
Sapphires and rubies have always been considered one of the... They belong to the same variety - corundum, but have different colors. In addition, as it turns out, only blue sapphire belongs to the category of precious stones. When buying any of these stones, you can often run into synthetic corundum. What is he like?
Synthetic corundums
Most people assume that synthetic stones are fake. Actually this is not true. Such a stone is a complete analogue of a natural one, only grown in a laboratory. its composition is similar to natural stone in structure, optical, physical and chemical properties.
There are several methods for extracting artificial corundum that are used in industry:
- Czohalski method;
- zone melting method;
- obtaining from the gas phase;
- hydrothermal;
- from solutions in the melt.
Since each method has its own technology, the end result is different. With the help of special equipment, you can not only see that the stone is not of natural origin, but also determine the method that was used to create it.
The stone can imitate natural minerals or have shades that are not found naturally. Among natural stones, artificial corundum replaces:
- Colorless stone. It was formerly used as, but was later replaced by cubic zirconia, due to the fact that it had a higher refractive index and cheaper production technology.
- Red. This color of artificial stone is used instead of ruby; sometimes it can also be used to imitate garnet or spinel, but rarely.
- Dark red is used to imitate stones such as pyrope and almandine. But most often they are replaced with dark red quartz.
- Pink; imitations of other stones are made from a mineral of this color - topaz, tourmaline, beryl.
- Orange color is used to create types of sapphires - padparadscha, hessonite, and also as an imitation of hyacinth.
- Yellow. Padparadscha, as well as yellow topaz and heliodor.
- Green. Chlorosapphire, imitation emerald, chrysoberyl, demantoid.
In addition, synthetic corundum is used to create stones, which have their own trade names:
- Rose of France. Corundum is lilac-red in color.
- Damburite is a dark yellow stone.
- Rosolin - dark pink.
- Medeira topaz is yellow-brown.
- Palmyra topaz - brown.
- Amaryl - pale green.
- Burmese sapphire - blue.
Recently, high-quality rubies and sapphires with the effect of asterism have begun to be produced. In such stones, inclusions in the form of rutile crystals, which are arranged in a certain order, create a star-shaped effect with a different number of rays in the center of the stone. To simulate this effect, a molten solution is injected into titanium oxide.
In industrial settings, an ore called bauxite is used to create corundum. It is melted and then crystallized in an oxygen-hydrogen flame in electric furnaces. Furnaces also contain a reducing agent in the form of iron filings.
In order to obtain a red stone, which will later be used as a ruby, chromium oxide is used. All yellow sapphires are produced using nickel oxide.
If you add vanadium oxide during the manufacturing process, the stone will have a reddish-yellow color in daylight, and red in artificial light. The green tint is obtained by adding metals such as magnesium, cobalt and zinc. Chrome and iron produce red colors and are used to produce synthetic rubies. Titanium is used to give corundum the color of sapphire blue. And with the help of three metals together they make purple-colored stones.
To obtain a uniform color, refining methods are used that are applicable for natural corundum: diffusion and annealing. Although in fact both of these methods are based on the physical phenomenon of diffusion, simply annealing stimulates processes inside the stone. Moreover, the depth to which the color penetrates into the stone depends on the size of the dye molecule. During annealing, the entire stone is filled with color to its full depth, and during diffusion - partially. Therefore, the second method is not durable; the color may come off when the stone is re-cut and polished.
History of cultivation attempts
The first attempts to recreate copies of precious stones most often consisted of simulating gems with glass; in rare cases, crystal was used. In parallel with science, alchemists also worked in this direction, but their experiments also did not yield anything. The breakthrough came in 1892, when Verneuil first grew a 10-carat ruby in the laboratory. It was the discoveries made by this chemist that laid the foundation for a new industry in the production of stones.
The positive side of the process was not only that beautiful jewelry would be available to a wider range of people, but also that the stones could be used in industry.
Modern methods are based on the same Verneuil method, but now, thanks to some adjustments and modifications, it has become possible to recreate a much wider range of synthetic stones.
Even diamonds are now obtained artificially. But this is done under very high pressure, so they still have a price that is only slightly lower than natural ones. The exception is a stone of completely natural origin - pearls. The process of creating pearls by human hands takes place in the same mollusk shell.
At first, jewelers were wary of such technologies. They were afraid that the stones would be indistinguishable from real ones, so as new technologies for producing synthetics emerge, work is underway on methods to distinguish them.
How to distinguish artificial corundum?
There are a number of ways to distinguish corundum from a fake. In the case of artificially grown stone, everything is somewhat complicated. Visually, the synthetic mineral looks more beautiful, its color is deeper. Defects are common in natural stones. These can be either inclusions or cracks.
It is impossible to give a 100% guarantee using visual methods alone. However, there are some distinctive features that suggest that the stone was born in a laboratory:
- Artificial gems may contain inclusions in the form of air bubbles; you can notice them if you examine the stone with a magnifying glass. Such bubbles are also present in natural stone, but in artificial stone they have the shape of a sphere.
- If you look at sapphire under magnification, its color is not very uniform; you can notice alternating darker and lighter stripes.
- In some sources you can find statements that supposedly natural stone is harder, but this is not always the case. This testing method will only be suitable for distinguishing sapphire from its imitations; artificial stone can often be even harder.
- A natural sapphire or ruby can have a variety of inclusions. These can be zircon crystals accompanied by black voids, other crystals, as well as substances in another phase or in several at once.
- The cut that is used for natural stones plays an important role, while synthetic stones can be cut according to different rules, for example, depending on the shape of the source material.
Laboratories use methods that are based on determining color, growth lines and the composition of inclusions. In order for the results to be reliable, it is necessary to use equipment that can only be available to the most renowned laboratories.
Application
There were no sources of natural rubies and sapphires in the USSR, so almost all of them were artificial. Although this was not reported in stores, they were sold as if they were real. Therefore, now many people, having inherited the rubies of their grandparents, are surprised to discover that they are not real.
Ring with synthetic corundum
Everyone probably remembers the “twelve ruby watch,” an inexpensive but long-lived mechanism. Obviously, not real stones were used for production, otherwise the price of such a product would be tens or even hundreds of times higher. The main advantage of such watches was the high hardness of the synthetic mineral, which was presented in the form of films. Unlike crystal, which was also used in this area, they were not as susceptible to abrasion.
Even now, plates made of synthetic corundum are widely used in the field of medicine. They are used to make implants and surgical instruments. While a steel scalpel reaches a width of several minimeters, a sapphire one can be only a couple of microns. It doesn't actually cut the fibers of the flesh, but pushes them apart. Sapphire implants are very popular due to their high chemical inertness. They are also used as a thin heat-insulating coating.
Unfortunately, it is now rarely possible to buy a ruby or sapphire of artificial origin of normal quality on the market in our country. The fact is that the technology from the times of the USSR was sold abroad, and today’s stones are made there. And here comes the actual marriage.
This situation has already been observed several times when synthetic rubies came on sale, having inclusions similar to natural ones, and were hardly distinguishable at all. Moreover, they were removed from the auction virtually at the last moment.
So, if you have jewelry with a synthetic ruby from the times of the USSR, do not rush to sell it, since the price for it will be low, and very few can afford natural rubies.
But you can sell some other corundums, for example, imitation alexandrite, they cost practically nothing.
Thus, a synthetic stone is not a fake, but only an analogue of a natural one, obtained artificially. Synthetics cannot be distinguished by any physical characteristics of the mineral, only by the nature of the inclusions. They are no worse in properties than natural rubies and sapphires, but are less valuable because they were not grown by nature.
Corundum stone is a collective name for several types of minerals well known to us. By and large, they differ from each other only in color, depending on the presence, type and amount of impurities. Let's look at the types and properties of corundum stones: what abilities they have, how they are used and who they are most suitable for.
Description and varieties
Corundum is a natural stone consisting of aluminum oxides and various impurities. The mineral can be coarse-grained or fine-grained. It is distinguished by its high hardness, which is second only to the hardness of diamond. In the absence of impurities, it has a pale grayish color, and sometimes is completely transparent. Impurities of iron, chlorine, vanadium, chromium, etc. color it blue, red, yellow and green in various shades.
Varieties
Not everyone knows that corundum is both ruby and sapphire, and some other varieties of them. In jewelry production, they prefer to be distinguished separately, although in fact they are the same stone of different colors.
Brightly colored, high-quality corundums are considered precious gems of the first order.
Ruby
Red corundum or ruby is one of the most famous and popular gemstones. In ancient times it was called “yakhont” or “yar” for its bright fiery color. It is transparent and can range in color from pink to dark cherry and red-violet. This is usually the most expensive corundum, especially its bright red and star varieties.
Sapphire
No less popular in jewelry circles is blue sapphire - also corundum. Its color range can vary from pale blue shades to dark blues. The most expensive and sought after are deep and bright blue colors and cornflower blue shades, like Kashmir sapphires. The mineral gets its blue color due to the admixtures of titanium and iron. However, there are not only blue sapphires - stones with this name can be painted in other colors.
- Green - it is called chlorosapphire, because chlorine impurities give it green tints. Sometimes this stone can be confused with an emerald - in the old days it was called the “oriental emerald.” It is found quite rarely, and therefore is highly valued.
- Transparent is also a rare and valuable variety, known as leucosapphire. Outwardly, it resembles a diamond - previously such stones were called oriental diamonds.
- The yellow, orange or pinkish pebble has the luxurious Indian name “paparaja”. Large and rich gems of this variety are highly valued.
- Violet – This stone is very similar to amethysts and is often called the “oriental amethyst”. However, it is also a type of sapphire.
Synthetic corundum
The description of this group of minerals would not be complete without mentioning artificial corundum - grown in laboratory or industrial conditions. This stone is also called synthetic or synthesized. It would be a mistake to think of it as a fake or fake - it is not glass or a piece of plastic, which people sometimes try to pass off as natural stones. Synthetic corundum is created by melting and recrystallizing alumina raw materials obtained from bauxite (aluminum ore). To give the desired color, appropriate admixtures are used.
A small crystal of corundum is used as a seed. The aluminum oxide powder melts and drop by drop increases the volume of the seed - this is how the synthetic crystal grows. The color of artificial stone is more saturated and bright than that of natural stone. There are no natural defects in it, such as cracks and foreign inclusions, but there may be bubbles formed during production. Otherwise, the properties of natural and artificially grown corundum are practically the same, but the first minerals are traditionally much more expensive than the second.
Price
Ruby
As already mentioned, the most expensive corundum is ruby. The range of prices for stones with different characteristics is very wide. In addition to color and quality, the cost is affected by the size of the pebble and the presence of heat treatment.
If the weight of a gem reaches 5 carats or more, its price skyrockets and amounts to tens and hundreds of thousands of dollars.
Large corundums of bright red color are extremely rare, and therefore they are valued even higher than diamonds.
The cost of a stone that has noticeable defects is 30 - 50 dollars per carat. Good quality heat-treated rubies are valued at $2,000 to $20,000. A gemstone that cannot be heat treated costs from 5 to 70 thousand dollars per carat.
Sapphire
The most expensive stones have a rich cornflower blue color, large size, no defects, and “star-like” appearance. Untreated specimens, which naturally have a deep color, are several times more expensive than artificially refined ones.
The lowest quality stone can be purchased for $20-40 per carat. An example of average quality costs from 50 to 500 dollars per carat. Good quality sapphires are priced from $700 to $4,000 per carat. High-quality specimens reach 6 thousand dollars, and especially large ones – 20 thousand dollars.
Application
Jewelry
Sapphires and rubies are among the most common stones in jewelry production. High-quality corundums are used to make luxury and status jewelry (this could be a ruby set, earrings with Kashmir sapphires, a bracelet studded with stones, a ring with a large insert, etc.). Expensive gems are set in gold or platinum and combined in products with diamonds or other precious stones.
However, this does not mean that corundum can only be found in elite and expensive jewelry. Light pink rubies, pale blue and dark blue sapphires, whose main difference is their moderate price. The following products are often found: small silver earrings, thin rings, pendants with small inserts.
Transparent corundum is usually cut into round, oval, square or trillion, and star minerals are cut into cabochons to enhance their unique patterned beauty.
Other uses
The use of corundum does not always apply to jewelry. In addition to creating sapphire and ruby jewelry, the mineral is used in electrical engineering, medicine, mechanical engineering, and the chemical industry. In metal processing, corundum is used to make grinding tools.
Many people know about the use of corundum in the construction of devices - extremely resistant sapphire glass has long been used for cameras, smartphones, watches, etc.
In medicine, the mineral is used to make implants, in particular orthopedic and dental ones.
The amazing strength of this material makes it possible to produce super-thin surgical instruments that allow complex operations and wear out much more slowly than steel ones.
Healing properties
The significance of this mineral for health and healing largely depends on its color. Red and pink stones tend to improve blood circulation and metabolism, increase immunity and overall tone. Blue minerals have a beneficial effect on vision, help with eye fatigue, and normalize intraocular pressure.
Yellow and orange - promote rejuvenation of the body, improve the functioning of the digestive system. Purple corundum is a good remedy against depression and melancholy. It helps in solving psychological problems and treating mental illnesses. Green pebble can heal respiratory tract diseases and heart diseases.
Magic properties
Each of the gems has a beneficial effect on the energy of its owner, namely on the work of a specific chakra with a similar symbolic color. By nature, this mineral is very active - it is suitable for active and enterprising people, as well as those who want to develop these qualities. A talisman with this mineral will help you cope with laziness and bring the job you started to a victorious end. The pebble helps everyone who strives for self-improvement - in professional activities, creativity, sports, etc. It will help a person become a true master and expert in his field.
As a talisman, the mineral helps cope with anxiety, irritation and nervousness. It promotes philosophical reflection and analytical thinking, broadening one's horizons and a deep level of communication with others. Such a talisman is indispensable for doctors, psychologists, teachers and businessmen, but for people of other professions it will also be useful. Among other things, red ruby has the ability to revitalize love relationships, endowing them with passion, energy and new fervor.
AND . But let's start with the base of the stone.
What is corundum?
From a chemical point of view, the hero is an oxide. Corundum formula: - Al 2 O 3 . In its pure form it corresponds to leucosapphires.
This is the name given to the colorless variety of the mineral. Sapphire, that is, ordinary, “polluted”. s and scarlet.
The photo shows a raw corundum crystal
Red corundum called ruby. Yellow-brown padparadschas owe their color to divalent, and trivalent does.
Opaque, corundum stone called emery. It is rarely a separate mineral. Usually, this is a rock, that is, oxide combined with other stones.
This corundum is a little more pliable, but is also capable of abrading surfaces. The only material that is not amenable to the hero of the article is . Why? Let's find out further.
Properties of corundum
Always on the sidelines. Doomed to this corundum. Properties minerals are slightly inferior to diamond, but in no way “outdo” it. Diamonds have a maximum .
It is equal to 10. Corundum is given 9 points. Some varieties, due to impurities, are even softer. As a rule, this is .
However, the total mass of corundum is assigned a 9. She doesn't let you scratch. This can only be done, but there are few surfaces decorated with it; it is unlikely that you will have to fight against them with sapphires or padparadschas.
The presence of the hero of the article of almost record-breaking and nondescript varieties made it possible to use it as an abrasive.
Modern emery is a mixture of corundum and . But, in the old days, pure corundum was called emery.
The modern name for the mineral was given only 2 centuries ago, when the representatives of the mineral group were generalized.
The temperature at which precious corundum melts. You need a heat of 2050 degrees. However, the delight subsides when you remember that they melt only at 3,700 Celsius.
Such temperatures indicate deep formation of minerals, where they can crystallize among hot magma.
Corundum is resistant to temperatures, but not its color. When heated, the mineral loses its colors. The result is colorless leucosapphire.
It is also possible to enhance the color of the stone. Exposure to radiation is required. Processing it is a difficult and dangerous matter. Not many people decide to experiment.
Warming up corundum crystals reluctantly release heat to the environment. Therefore, the mineral is used as thermal insulation. Corundum for it they take a thin one; even a coating based on stone chips will do.
In this he is inferior to the hero of the article. Thermal conductivity is many times higher. True, if the indicator were different, use for insulation would remain economically unprofitable.
In the photo there is blue corundum
Corundum – mineral, which is superior in density. For aluminum oxide it is 4 grams per cubic centimeter, and for the king of stones it is 3.5.
Accordingly, natural, or synthetic corundum heavier 1, that is, 200 milligrams of the hero of the article in a volume less than a carat.
In terms of sparkle they outperform corundums. The refractive index of the latter is 1.8. Diamonds have a mark 0.7 higher.
But, they don’t have such rich and deep ones. That's why colorful things are valued corundum. This is natural stone, enchanting with the depth of color and its tints.
They can be iridescent, visible on chipped crystals. Also, crystalline aluminum oxide is distinguished by birefringence, that is, the splitting of light streams in two.
At the same time, the lengths of the resulting rays do not coincide. In the world, this phenomenon is most pronounced in the optical.
Once you look at a drawing through a crystal, you will see two lines, or two images.
In addition to the impurities that give corundum its color, inclusions may be found in it. It is titanium oxide that crystallizes in the form of stones.
They grow into corundum along the main directions of its lattice. As a result, the results are peculiar, which look through the hero of the article, enveloped in “clouds” of light. The effect is called asterism. It does not appear in diamond.
The photo shows green zoisite with red corundum in the center
Chemically, corundum is resistant, which confirms its “indifference” to acids. In their environment, the stone remains intact and preserves.
Corundum shine, by the way, comes in several types. Most often, the luster is glassy. But there are also samples with a metallic and diamond shine.
Mining and deposits of corundum
Oxygen, which is part of the hero of the article, is the first most common on the planet. Aluminum took 3rd place. element yielded .
It turns out that both components of corundum are not deficient. Accordingly, the hero of the article is found frequently and is distributed everywhere. The only question is the quality of the stone.
You can find something to use everywhere, but you have to look for crystals. In, for example, there are almost none. The samples found are not enough for industrial production.
Thus, pink corundums are found in Karelia and the Urals. They are rare and valuable, but only if they are transparent. Among the Karelian and Ural samples, only a few can be seen.
Therefore, buying , , ring with corundum, in 75% of cases you get an Australian one. The remaining 25% of corundum is mined in India, Africa, Turkey, USA, Thailand and Canada.
Corundum crystals are hexagonal. They come in two types. The first is plates, the second is elongated barrels or bipyramids.
The latter are two volumetric ones, fused at their bases and with their apices facing in opposite directions.
On photo corundum appears, as a rule, in the form of crystals. They are spectacular. However, in nature, granular accumulations are more often found mixed with host rocks.
The role of the latter is usually played by. Of the minerals accompanying corundum, it is worth listing all types. If you found them, you will probably find corundum too.
Not everyone goes into the natural environment for corundum. Synthetic crystals have been produced since 1877. They are invariably transparent, clean, and the color saturation can be adjusted.
This type of regulation is popular in Switzerland and Switzerland. As you can see, in the forefront of the country with meager reserves of jewelry-quality corundum.
Synthetic stones are also in demand outside the sphere. Abrasive materials have already been mentioned. But there are still some areas of application for aluminum oxide. We will devote the next chapter to them.
Application of corundum
While some are looking earrings with corundum, while others run into construction shops for sandpaper, while others study gadgets with glass.
They are continuous sections of transparent crystals. This type of glass is harder than mineral glass, which means it is more scratch resistant.
sapphire. It's cheaper and cleaner. In addition, growing crystals of a substantial diameter is a matter of couples, but finding them in nature takes decades.
The industrialists' reason is clear. However, it deprives the goods of magic and healing properties. According to esotericists, they are possessed only by natural corundum. Buy They seek it in order to normalize blood pressure, help work, and get rid of mental disorders.
The nuances of the effect on the body depend on the color of the mineral. crystals are responsible for the circulatory system, blue ones improve vision. It is better to restore the psyche with purple corundum., especially gender. Corundum drives them crazy.
For other signs, the hero of the article is neutral, a beautiful addition to the image, but not a magical attribute.
Corundum price
Corundum price depends on the type of stone. Technical stones are sold in tons. Taking about 20,000 rubles for 1,000 kilograms.
In the case of jewelry crystals, you can pay so much for a couple of carats. If we take the average price tag, the most expensive corundums are rubies.
In second place are crystals. Next come sapphires. The yellow padparadscha got .
In the photo there is a ring with corundum
Unprocessed corundums, even precious ones, can be taken profitably provided the stones are cloudy and have internal defects, for example, cracks.
Thus, a piece of ruby 3 by 2 centimeters will be included in the mineralogical collection for only 300-500. An unprocessed crystal is also suitable as a homemade one.
An imperfect stone is unlikely to be grown in a laboratory, which means it can fill life with magic and health.
