Precious metals and alloys. What are precious metals and what is their value

From ancient times to the Middle Ages, mankind believed that there were only seven metals, each of which was the conductor of one of the then known planets. Among them were those with extraordinary properties. They continued to shine in the air and after a long stay in the water, they did not succumb to the action of caustic alkalis, acids and high temperatures. For such a combination of constancy and perseverance, inherent in perfection, they were called noble metals.

Needless to say, the value of such metals was very high, and the more such a metal a person owned, the richer and more powerful he was. Therefore, due to their high cost, they received a second name - precious metals.

Of the seven metals of antiquity, only two, gold and silver, were considered noble. Already much later, only in the 18th century, platinum and its satellites were discovered and added to them. So what are the qualities of the metals included in this elite group?

Precious metals are the most chemically resistant, corrosion-resistant and non-oxidizing metals, which distinguishes them from other known metals. The reserves of such metals in nature are small, they are found in various ores or in the form of nuggets, in addition, the process of their extraction and extraction is quite laborious. Thanks to these unique qualities, as well as the beautiful brilliance and appearance of products made from these metals, they deserve their name.

Naturally occurring precious metals include gold, silver, and the platinum group metals: platinum, osmium, iridium, ruthenium, palladium, and rhodium.

There are precious metals, the so-called isotopes, obtained artificially in special laboratories. The most expensive such metal is californium-252, and the most popular is osmium-187. Some scientists also classify the rare and radioactive technetium as a noble metal.

Natural noble metals and their features

Rhodium

Most people still consider gold the most precious and rare metal. But in reality this is not so, there are more expensive and valuable metals. Rhodium comes first. A noble metal of silver color with a bluish tint was discovered in 1803 in England. The cost of rhodium is about $230 per 1 gram, so it is used only where it is impossible to find analogues for it. Such a high cost is due to the fact that rhodium is the rarest element that does not have its own minerals.

This metal, in addition to its high cost, is characterized by extremely high resistance to the effects of aggressive environments and high temperatures. At the same time, the distinguishing feature of rhodium is its extreme fragility.

Platinum

The second place in value is occupied by platinum, which was known in ancient Greece, Egypt and South America. As a new chemical element, it was introduced in 1952 by the Swedish chemist Schaeffer.

Platinum is a rare precious metal found in nature only in natural alloys with other metals. The process of obtaining it is extremely time-consuming and costly. The features of platinum include its increased chemical resistance, it is not affected by any single acid. In addition, at the strongest incandescence, it does not oxidize in air and does not change its natural silvery-white color.

Gold

The main precious metal in the world is, of course, gold. It is ranked among the seven metals of antiquity, known since the Stone Age. In nature, gold occurs in its native form with small amounts of impurities and in the form of a natural alloy with silver.
Gold is distinguished by its exceptional thermal conductivity and very low resistance. An exceptional feature is its malleability and malleability, in addition, it is a very heavy metal. With all this, gold is inferior to most of the noble metals in terms of strength and chemical resistance.

The largest gold nugget in the world, found in Australia, weighed almost 90 kg. It was given the name "Holterman Plate".

Osmium

Osmium is the heaviest precious metal, discovered in 1804 in England. This silver-gray metal is not found in its pure form in nature. Its rarity is the main reason for the rather high cost, and therefore its use is extremely limited.

Despite being the heaviest metal, it is extremely brittle. In addition, it has exceptional hardness and refractoriness, these are one of its main advantages.

Iridium

Iridium, discovered in 1804, also belongs to heavy metals. In nature, this silver-white precious metal is extremely rare, and is considered one of the least common elements.

Iridium is a very strong but brittle metal. In addition, it is characterized by increased hardness, due to which it is difficult to machine.

Ruthenium

Among noble metals there is a metal named after Russia, it is ruthenium. Discovered in 1844, ruthenium is the rarest element of the platinum group.

Its most valuable properties include refractoriness, as well as chemical resistance. This precious metal is also distinguished by its hardness, combined with extreme fragility. In addition, ruthenium is able to act as a catalyst in some reactions.

Palladium

Palladium is the lightest precious metal. In 1803, it was discovered by the Englishman Wollanston, who brought it from America. In nature, palladium is found in the composition of copper-nickel ores, therefore it is more accessible and cheaper than other platinum metals.

The features include its flexibility, ductility and resistance to corrosion. The main unique ability of palladium is the ability to dissolve hydrogen and exceptional fusibility.

Silver

And finally, silver, since ancient times a well-known precious metal found in nature in its native form. In addition to silver ores, which contain more than 50% of this metal, there are also complex ores, the silver content of which is lower, but it is from them that the main production occurs.

Silver is a soft and ductile metal that reacts most actively in chemical reactions compared to other precious metals. In addition, silver is an exceptionally thermally and electrically conductive metal.

Applications of precious metals

The areas in which precious metals have found their application are extremely extensive. And if in ancient times the main ones were coinage and jewelry, in which gold and silver found their place, now the scope of existing precious metals is quite wide. This is due to the fact that they have exceptionally useful qualities that other metals and materials do not have.

This includes the automotive industry, which uses rhodium, platinum and palladium to produce automotive catalysts and catalytic converters. And microelectronics, nuclear tests in the nuclear industry, jewelry production and even dentistry, in which, due to its properties, there is a place for gold.

Precious metals find their use in chemical and petrochemical industries, such as osmium and iridium. And also in biomedicine and aerospace instrumentation, and even in the production of such military weapons as lasers.

Coinage, photography, electronics, laboratory glassware, mirror coatings, and the radio industry are just a few examples of precious metals such as silver and ruthenium. And such a rare element as osmium is indispensable in the pharmacological industry; without it, the production of cortisone is impossible.

In addition, precious metals are widely used in the glass industry. They are used in the manufacture of liquid crystal displays, fiberglass and optical glasses.

Metal as an investment

Precious metals are also actively used as an investment object. Today, everyone can afford to have their own “gold reserve” by investing in investment precious metals, which include gold, silver, platinum and palladium in bars and coins of high quality.

In addition to the traditional ways of investing in the form and coins, Russian banks are opening. Physical metal is good for a long-term investment, you can get a tangible profit with sufficient exposure to the asset. The second method has such a disadvantage as the lack of deposit insurance, which introduces a considerable risk.

Copper in the modern world can be considered a precious metal. And the largest companies from the metallurgical sector understand this. Anglo American and Glencore are ready to sell assets related to iron ore or coal, but they do not intend to part with copper.

The whole reason is that By the end of this decade, the world will face a serious shortage of copper caused by a drop in investment in the sector some time ago.

Even Rio Tinto Group, one of the largest mining and metals companies, announced the appointment of the head of the copper division as the next CEO.

And BHP Billiton is also focusing on the metal, as evidenced by an additional $10 billion investment through dividend cuts and capex.

Anglo American, for example, refused to sell copper mines, referring to the fact that these are the most important world-class assets, on which the entire copper strategy is built, but due to excessive leverage, credit ratings have now been cut to "junk" levels.

The total value of M&A transactions in the sector reached $3.1 billion in 2015, the lowest level in 5 years, according to Bloomberg data. According to Ernst & Young, only 27 deals were closed during the year, compared to 38 for coal companies and 117 for gold mining companies. The low level of activity is most likely due to the lack of funds in the market.

Market participants themselves say that there are quite a lot of negotiations, but there are almost no real transactions, since sellers and buyers have different price expectations.

Copper companies are waiting for a rebound in copper prices this year. The value of the metal rose 19% from its January lows, and the quarter's rise was the first in almost two years.

Now metallurgists pin their hopes on copper, as this will allow you to pay off your debts and improve your position in the face of falling demand for metals.

However, not everyone shares this optimism. According to Goldman Sachs, "bears" will remain in the copper market until 2018, while Barclays predicts a decline to $4 thousand per ton. Now a ton of copper costs about $4.78 thousand. Since March 17, the metal has already lost 6%.

Perhaps it is the recession that will prompt companies to sell copper assets. In the first quarter, transactions worth $1.8 billion have already been completed, but so far we are not talking about large and main assets on the market. Large companies do not want to buy "garbage", they will wait for the really valuable assets to appear.

Scientists have proven that copper can replace gold and silver in photonic devices

Russian scientists from the Moscow Institute of Physics and Technology during the experiment proved that copper can completely replace silver and gold in photonic devices. Previously, it was argued that only nanophotonic components based on gold and silver can be successfully used in photonic devices.

The revolutionary discovery of Russian scientists proved that copper can become a worthy replacement for gold and silver in photonic devices. As previously thought, all other metals, except for gold and silver, have a large absorption. As for the practical side of the issue, it is extremely difficult to make components based on these two metals because of their peculiarity not to enter into chemical reactions. This not only makes it difficult to create nanostructures, but also makes the process very expensive.

precious metals- these are metals with high chemical resistance, which practically do not oxidize in air and are not subject to corrosion, and products made from these metals have unique properties and a characteristic "noble" luster. The main ones are: gold, silver, platinum. The value of these metals is due to the small size of their world reserves.

To major precious metals include:

• gold,
• silver,
• platinum Pt,

as well as the following platinoids or platinum group metals:

• ruthenium,
• rhodium,
• palladium Pd,
• osmium,
• iridium,
• rhenium Re.

Gold and silver are the most ancient precious metals known to mankind. In those distant times, they were very often found in native form - mining was easy and was not complicated by smelting from other ores. Due to their malleable qualities, gold and silver were easy to process, so they were used to make jewelry, cutlery and dishes, and in the 6th century, the ancient Lydians began to mint coins. Platinum was also known to the Ancient World, but the Europeans got to know it in the middle of the 16th century - at the time of the discovery of America. It is noteworthy that counterfeiters were the first to master the use of this white noble metal, similar to silver: they weighed coins with this cheap metal, at that time, but denser than silver and gold. As a result, the Spanish government banned the import of platinum into the country, and its stocks were dumped into the sea. Platinum is almost never found in nature in its pure form. Nuggets containing it, as a rule, are alloys with other metals - noble and base. Therefore, starting from the 18th century, the rest of the platinum group metals were discovered in turn.

Growth depends on several factors:

• supply and demand,
• mining,
• manipulation of government stocks.

The supply is limited by the rarity and uniqueness of precious metals, and the demand for them is constantly growing, since the specific properties of these metals are in demand in various fields: in the automotive industry, electronics and electrical engineering, in chemical engineering, in medicine, in the photo and film industry, and, of course , jewelry manufacturing.

Features of the extraction of precious metals doubly affect their world prices. On the one hand, the ever-increasing complexity of mining is labor-intensive and costly. On the other hand, leading positions in the extraction of precious metals are beginning to be occupied by developing countries, where labor is cheaper and more favorable tax regimes.

Despite the fact that since the beginning of the 20th century the gold standard has been abolished, most states continue to keep precious metals as part of their gold and foreign exchange reserves. The announcement of one of the countries on the sale of part of its gold reserves significantly reduces the price of precious metals on the world market.

Today, investments in precious metals are becoming popular in Belarus. In you can buy precious metals in ingots of different weights and coins. You can store them in the depository of the bank, earning on the rise in prices, while the benefits of such investments are in the long term. And you can also open a so-called “golden account” in the bank, on which grams are stored instead of money and grow in the form of interest.

Precious metals are noble metals that are not subject to corrosion and oxidation, it is these properties that distinguish them from other metals. Noble metals are considered precious due to their beauty, rarity and high corrosive value.

The main precious metals are considered to be: silver, gold and metals belonging to the platinum group: platinum, ruthenium, rhodium, palladium, osmium and iridium. precious metals have noble properties due to their high chemical resistance and beautiful gloss. All noble metals are practically not oxidized by atmospheric oxygen. Silver, gold and platinum have high ductility, while platinum group metals have high melting point.

Precious metals have been known to mankind for a very long time. In ancient times and until the middle of the Middle Ages, people believed that in nature there are only seven metals that are conductors of one of the planets known at that time. Of these, there were metals that had unusual properties. The properties of these metals were such that they shine for a very long time in air or when they are in water, they are not affected by the action of acids, caustic alkalis, and they are not affected by high temperatures. Of the seven metals of antiquity, silver and gold were considered noble and precious. Only starting from the 18th century, a small list of these metals was replenished with noble platinum and platinum group metals discovered at that time.

In addition to the main precious metals, there are also other precious metals. These metals include metals - isotopes obtained artificially. For example, one of the most sought-after metals is osmium - 187, the most expensive californium - 252 and the rare noble metal technetium.

Rhodium

Today, many people still consider gold to be a rare and noble metal. In fact, there are other more valuable and expensive metals. According to its value and nobility, the first place is occupied by platinum metal - rhodium. This metal was discovered in England in 1803, it has a silvery color, with a slightly bluish tint. Rhodium is used where it is impossible to replace it with other analogues. Today, the cost of rhodium is $230 per 1 gram.

Rhodium is an extremely rare chemical element in nature. Rhodium does not have its own naturally occurring minerals. This explains its high cost. In addition to the high cost, this metal is characterized by high resistance to various chemical influences and high temperatures. Rhodium is used very often for rhodium plating on silver jewelry. Such silver jewelry () plated with a thin layer of rhodium looks brighter than silver and has a more attractive appearance. However, rhodium is an extremely brittle metal.

Platinum

In second place in value is platinum. Platinum is a noble metal that was discovered by Europeans - the pioneers of new lands in America. However, platinum has been known for a very long time. Platinum has been known since ancient Greece and Egypt. For a long time, the properties of open platinum were unknown. People did not know how this metal could be melted, since its melting point was very high. Platinum as a chemical element was introduced only in 1952.

Precious metal - platinum is a rare precious metal that occurs naturally in the form of natural alloys with other metals. Obtaining platinum is a very laborious and costly process. Platinum is a highly inert metal. Platinum is not affected by any single acid. Even with strong incandescence, platinum does not oxidize in air. Strongly calcined platinum, after cooling, retains its silvery-white color.

Gold

Gold is considered the world's most important precious metal. This noble metal belongs to the seven metals of antiquity, known since the Stone Age. Gold occurs in nature in the form of gold nuggets with a small amount of impurities or in the form of natural alloys of gold with other metals, for example, an alloy containing gold and silver or other metals: copper and iron.

Gold has unusual properties that distinguish it from other metals. It has low electrical resistance and is a good conductor of electricity and heat. Gold is a highly ductile metal, it is well processed, has excellent malleability and malleability. However, gold is a highly dense metal and is considered a heavy metal. Gold, in its strength and chemical resistance, is inferior to other precious metals.

Osmium

The heaviest of all noble metals is the precious metal osmium. Despite its high mass, it is considered a very brittle metal. Osmium is a silver-gray metal. Osmium was discovered in England in 1804. In nature, in its pure form, osmium does not occur.

Osmium is a very rare metal of the platinum group, which has a fairly high cost. The high price of osmium limits its use. Osmium is an extremely brittle metal. Its main advantages are exceptional hardness and refractoriness.

Iridium

Iridium is a simple chemical element, a noble and precious metal of the platinum group, which has a high density and is considered a heavy metal. Noble iridium was discovered in 1804. Like other metals of the platinum group, the element iridium is extremely rare in nature. An exceptionally rare element - iridium is a silver-white metal. Despite its high strength, iridium is a very brittle metal. Iridium has a high hardness, which makes this metal mechanically difficult to process.

Ruthenium

Ruthenium is a noble metal that was discovered in 1884, named after Russia. Noble ruthenium is the rarest chemical element of the platinum group. Ruthenium has valuable properties: high refractoriness, chemical resistance, high hardness combined with brittleness. The element ruthenium is a catalyst for some chemical reactions.

Palladium

Palladium is the lightest precious metal. It was discovered by the Englishman Wollanston in 1803, who veiled it from America. Palladium is part of the copper-nickel ores. Compared to other elements of the platinum group - palladium, this metal is relatively inexpensive and more accessible for use. Palladium has unique chemical and physical properties. It is a flexible, ductile and corrosion resistant metal. The unique property of palladium lies in its ability to dissolve hydrogen in itself and is extremely easy to melt.

Silver

Silver is a noble and precious metal with a silvery-white color. This precious metal has been known for a very long time. Silver is an inert, slightly reactive and beautiful metal. In nature, silver occurs in the form of native silver. But in the native state, silver is very rare.

Silver mining is carried out from silver ores, which include up to 50 percent of silver. Silver is mainly mined from complex or polymetallic ores. Silver in polymetallic ores is contained in small quantities. The main one falls precisely on these complex ores.

Silver is a fairly soft and ductile metal that is easily processed, melted, mixed into alloys with other metals and does not oxidize under normal conditions with oxygen. Compared to other precious metals, silver is more active in chemical reactions. Silver has very low electrical resistance and is a good conductor of heat and electricity.

The use of precious metals

Precious metals, mainly gold, perform and maintain the function of money. Silver, which previously actively performed the function of money, after the saturation of the market gradually lost its significance as a material for making money. Today, precious metals are becoming increasingly important in various industries.

Noble metals in the electrical industry are used to make electrical contacts with a high degree of reliability. For example, silver contacts in electrical circuits have high corrosion resistance and resistance when a short-term electric arc acts on the contact surface. Alloys of various precious metals: an alloy of silver with gold, gold with platinum, silver with gold and platinum, are used in the technique of low currents at low voltages.

Precious metals, having great chemical resistance, are used in laboratory technology and chemical engineering. Noble metals are used to manufacture parts that are often exposed to various aggressive environments: electric heaters, retorts, high-temperature furnaces, thermocouples and equipment for the manufacture of optical glass, distillers, autoclaves, furnaces, ladles, flasks, special chemical laboratory glassware designed to work with various aggressive acids and alkalis.

Noble metals are used in medicine for the manufacture of various medical instruments, various parts for medical devices, prostheses, as well as various preparations, mainly made of silver.

Gold doped with germanium, silicon, indium, gallium, selenium and tin is used to make contacts in semiconductor diodes and transistors. Silver salts ( , ) are raw materials for the manufacture of light-sensitive materials.

Precious metal alloys are widely used in jewelry. Solders with silver are used for soldering various structures where it is necessary to ensure high strength and reliability. Some noble metals have high catalytic properties.

Precious metals and alloys

physical characteristics

Jewelery is called made of precious metals and stones,as well as from other durable materials, withcondition of their highly artistic processing.

Precious metals include: gold,silver, platinum and platinum group metals(iridium, palladium, osmium, ruthenium, rhodium), and also their alloys.

Precious metals have a beautifulappearance, good gloss, chemical and weather resistance,strength and high hardness. These virtueswa precious metals led to their use inas a material for making jewelryproducts. To increase the strength of precious metalsused in the form of alloys.

Gold is a very soft, malleable metal,with significant mechanical strength stu. It has a pure yellow color when ingots.strong metallic luster. admixture of silverra or platinum weakens the yellow color, and adding Copper plating gives gold a reddish tint. The melting point of gold is 1063 °C.

When cold, it has excellent cobone (allows you to get sheets up to0.0001 mm) and the property in drawing to stretch into a wire with a cross section of 0.05 mm or less. Onea gram of gold can be drawn into a wireabout 1 kilometer long.

Gold is chemically stable, with oxygenair is not connected. Dissolves in mixturetwo strong acids: 1 part nitric and 3 parts colyanoy ("royal vodka").

In nature, it is found mainly in non-ferrous metal ores and in the native state, and in a wide variety of forms - in the form of crystals, plates, flakes, fibers, grains, pieces and pieces weighing from several grams to several kilograms.

Platinum- silvery-white metal with graytym shade, in color and brilliance reminiscent oftin. In the native state in nature, almostnot found, platinum is minedwashing of platinum-containing sands. In sour takh (except "royal vodka") is insoluble. For

increase in hardness and strength, it is alloyed withgold, silver, copper or board metalsnew group - radium, iridium, palladium.

In jewelry production, platinum is usedused as a setting for diamonds and made for:combined (composite) products. ApplyIt is usually 950 platinum alloy.

Palladium- Silvery white metal.Occurs naturally in naturealong with platinum. Has a significant malleabilityductility and ductility, melts at a temperature1554 °C. It dissolves in nitric acid and aqua regia.

Applied to making jewelryproducts in alloys with gold ("white gold"), andit uses the bleaching abilityplatinum group metals.

Palladium is the youngest of the precious metalsused in the jewelry industry.

Mainly used palladium alloys 500 and 850 samples.

Osmium, ruthenium, rhodium - refractory shinyother platinum group metals silver-white color logo. In nature, they are found together with paynoah ("platinum satellites"). In jewelry practiceIke are used as decorative melting points (soldering) on ​​gold items, as well as inthe form of components to increase the hardness and strength of other precious metals or changeprecious metal colors.

Silver- shiny, white, very malleablemetal. In nature, sometimes found in nativeform, but most often it is part of the polymertall ores (lead, zinc, silver),Of all metals, silver has the highest reflectivity: it reflects 94 percentrays of light falling on it. Let's take it wellpolishes, melts at tempera 960,5 °C. Reacts with sulfuric and nitric acids.

In jewelry, it is most often used in alloys with copper, and in its pure form - for seribs of base metals. Products fromsilver issued in Russia before 1927, javantique, have a spool sample.

Precious metal alloys

Most precious metals havesuch a high degree of malleability, toughness and thickness that their use in its pure form is practicallytechnically impossible, therefore, in the jewelry industry in industry, dragme alloys are mainly used thalls formed by the fusion of one or morehow many metals with each other or with non-precious non-ferrous metals.

Alloys of gold

From a large number of gold alloys invery few are used in jewelry production. The components that make up the alloy (leaguetour), as a rule, consist of copper, bronze or brass.

For jewelry makingnew use of ternary alloys - gold, seribs and copper, less often double - gold with silver, gold with copper, gold with palladium or platinum and etc.

Silver alloys

In the jewelry industry, the most often used copper-silver alloys 875° (sample), for making silver items Liu with enamel coatings - alloy 916 °, for filigree products - 960 ° and above.

Platinum alloys

White alloys containing platinumused in jewelry to make verhushek, decorative surfacing (soldering) and oprav for precious stones (mainly - brilliants), as well as individual jewelry liy.

Alloys of "platinum satellites"

Palla alloys in jewelrydia, osmium, ruthenium, rhodium is given in the previous section.

Non-ferrous alloys

Base metals used in jewelernom production: bronze, brass and cupronickel.

Bronze- an alloy of copper with tin, aluminum andsilicon. It has a pleasant golden color, durable. Goes to art casting.

Brass- an alloy of copper and zinc, sometimes with up toby adding lead, tin, iron, nickel, or other metals called tompacami or semi-tompaks. Used to makemaking metal jewelry. It hasyellow, yellow gold or pale gold th color.

Melchior- copper-nickel alloy (80% copper +20% nickel). It has high ductility, is easily processed in a cold state, den for deep stamping. Cupronickel is usedzuyutsya as a frame for the reinforcement of crystal products. For the manufacture of various dining devices, cupronickel is used, followed by silvering.

Sample determination methods

To determine samples (sampling) of dredgesmetals and their alloys, there are the followingnew methods: gold chloride reagent, pro chemical reagents, on a touchstone, chemicalskim and muffle methods.

Under the conditions of customs control, it is preferable to test with a reagent of chloride gold and assay reagents.

Chlorine gold reagent

It is a solution of chlorine gold in water. It has a golden yellow color. Applies when testing gold bars and products from the bottomcoprob up to 600 samples, serves to determinemetal and, approximately, its samples before more accurate testing with acid testsbirch reagents.How to use: clean polished new or cleaned surface of the determined metal (alloy) a drop of reagent chlorine is appliedfoot of gold. On a surface wetted with a solutionMost metals quickly stainfrom the released precipitate of gold, the color of whichdepends on the impurity of the formed precipitate of the chloride salt of the test metal and acquirespersonal shades, by which the me talls.

On an alloy of gold 580-600 ° remains narrowlight brown rim all arounddrops. The lower the sample of the metal (alloy), the darker the spot.

Silver, copper, brass, lead blacken instantly

Table for the determination of metals with a reagent of chloride gold

Defined metal (alloy)	Color	Spot color from a drop of reagent	Spot formation time
high-grade silver	White	inky dark	Instantly
Aluminum and its alloys	White	Yellow, gradually darkens	Instantly
Platinum and its high-grade alloys	grayish white	No action
Tin and its alloys	White	Black	30-40 s
Zinc and its alloys	grayish white	Yellow, gradually darkens	Instantly
Brass	Yellow	Black, ink	Instantly
Base alloy of silver and copper	white yellow	Black	Instantly
Copper	Red	Black, ink	Instantly
White gold (583°)	White, grayish white	brown spot	2-3 s
Lead	bluish gray	Dirty yellow	Instantly
Pure gold and its high-grade alloys	Yellow	No action
Low-grade gold alloys (below 583°)	Yellow	Dark chestnut or green	5-6 s

Acid reagents

They are clear acidssolutions for testing gold alloys followtotal samples: 375, 500, 583, 750, 875, 900, 916, 958.Decompose quickly in the light and in open airspirit, therefore require storage in vials ofdark glass with ground stoppers. Storage period 3-4 months.

Chrompic (potassium bichromate) Orange solution, used fortesting of silver from 500 samples and above. On thealloys up to 750° two or three drops of chrompeak, opusswept sequentially to the same place andremoved with filter paper, leaves a light brown stain. On alloys and productsabove 750°, this reagent leaves red spots, which increase in brightness with increasingalloy sample. On items and alloys of 916 and above, chrompeak leaves a bright red spot.

Nitric acid silver

Transparent solution, made for the determination of silver samples: 750, 800, 875, 916, on whichremains a light gray spot. On alloys and productsin the lower samples - more or less dense white spots.

The order of storage of these solutions is the same,as for acidic reagents.

All reagents in contact with skin may cause burns, so when using them, you should be as careful as possible. Reagent, contact with skin, wash off immediately warm water with soap or soda (to neutralizeacid action).

Correspondence table of gold samples

Zolotnikova (Russia until 1927)
carat (foreign countries)
Metric (Russia,modern since 1927)	250	292	333	375	416	500	583	750	875	916

Table of correspondence of samples of silver

Zolotnikovaya
Metric	500	654	750	855	875	900	916	925	948

Note. The tables below contain only to the samples currently used and using previously sewn for jewelry production.

Samples of platinum and platinum group metals in tables are not given, because they are used in all wakh, samples of which are given directly in the descriptions these alloys.

samples

The advantage of the alloy from which platinum, gold, silver items are made, is divided by a sample showing the content precious metal in a conditional amount of weight units prostrate this alloy.

Until 1927 in Russia, the test was expressedwas the number of spools in one pound of alloy (1 pound = 96 spools). For example, gold alloy56 samples contained 56 spools of pure goldand 40 ligature spools (additional components tov) in the pound.

To convert a spool sample to metricwhich the following formula can be applied:

X \u003d 125 * A / 12, where X - metric test;A - gold sample.

Example: ring 56 spool test.

X \u003d 125 * 56/12 \u003d 583 °.

In England, USA and some other foreign countries In other countries, the so-called carat is usednew sampling system, in which 1000 metricsamples correspond to 4 carats. Should not betie this with a unit of weight of precious stones -carat equal to 0.2 g.

To convert carat to metricthe formula is applied:

X=125*B/13, where X - metric test;B - carat test.

Techniques of manual processing and decoration of precious metals

The techniques used inproduction of articles made of precious metals,various countries for thousands of years innew features remained similar. Almost the same descriptions of them with a difference only in details yes us in the "Natural History" of Pliny, a Roman writer who lived in I century AD e., in a treatise German whom the monk Theophilus, XI century, in the work on jewelrythe art of the Italian sculptor and jeweler XVI century by Benvenuto Cellini, in Russian manuscriptmanuals for masters 17th and 18th centuries kov and up to the present. The 19th century brought some mechanization into the methods of processing preciousprecious metals, which is mainly reduced to faster and cheaper production.

Below we will consider processing techniques.

Forging- was one of the first processing techniqueski of precious metals, which man recognizedcentury. It is based on the properties of gold and silver to flatten and stretch without breaking underpressure or impact.

Silver can be forged both cold and hot, gold - only cold.In order to forge a complex object, withchange hammers, coinage and anvil figures noah form.

Forging gives gold and silver density andelasticity. Forged items are different chaff natedsurface with soft shimmering glitter.

Casting- according to the antiquity of its originsecond only to forging. Due to the fact that goldthen silver melts relatively easily, casting is widely used in jewelry to makecooking both small and massivetools or their parts (for example, jewelry handleson the lids of the jars).

Thread- thanks to the softness of gold and silver, any images and ornaments can be laid down which are applied to their surface.

While chasing, basma, enamel is goodlook at a distance, as their beauty isnovel in the contrast of light and dark spots or in the contrast of different colors, the carving does not havebright decorative qualities.

The art of carving is an art especiallyrefined, fine lines carved into the metal,designed for close scrutinyclose admiration.

A special type of deep carving was called "Obron". With this type of carving, the background near the image or the inscription is "lowered" (collapsed) when the power of the cutter, thanks to which the image becomescurls a little more prominently.

Chasing- one of the hardest trickssilver jewelry, available far not for every master. Relief coinage is based on the property of gold and silver to stretchwhen struck by a hard object. Have a good master ra there were in the set several hundred coins of their own venous manufacture.

In XIX century, hand-chasing, where every smallest detail is made by hand, and therefore individual and unique, began to replace mechanichesky stamping and rolling.

Basma- I haven't found anything like this in any other country.distribution, as in Rus'. Basma - manualembossing images and patterns on thin sheetsgold and silver. Embossed patterns convey the plastic forms, but differ from coinage in somevagueness and softness of the relief.Due to the thinness of the sheet, Basma can easilybe crumpled, so it was more often used not fordecorations for household items, and for salaries of icons,details of iconostases, royal doors, icon cases, chairsComrade, church books.

Basma does not require a large amount of metal and therefore was widely used in ancient Rus'.

Scan- openwork or soldered on metalgraphic background patterns of fine gold, silveror copper wire twisted into a rope check or smooth. This is one of the most widespreadtechniques of jewelery known from ancient times. Inextricably linked with filigree on the grain- small shiny metallic beadsriks soldered onto a filigree ornament, or an independent decoration on the surface of the metal.

Scan is made from "purity", i.e. from pure gold lot and silver, which, due to the small amount or absence of impurities, are so softki that are able to stretch into a thin wire ku.

Solderis one of the most important techniques for filigree preparation and grain decoration. For a veryancient products, decorated with filigree and granulation, the solder is not visible at all, it strikes in them especiallynaya cleanliness and clarity of work. Until recentlyme, scientists struggled to unravel the mystery of the ancientsolder, since even modern X-rays Skye technology could not detect the places filigree and grain on objects, and only professionallitter F. Ya. Mishukov revealed the secret of solder. HowIt is said that everything ingenious is simple. Russian mas Tera mixed mercury, gold and silver in a certain fixed proportion, and then heated strongly,mercury evaporated, and gold and silver fused with the subject firmly.

Black- no other country has received such development, as in Russia, where it was famous for its specialstrength. Niello is a special alloy of sulphuroussilver, at first glance similar to coal, with made of silver, copper (tin), lead and sulfur in a certain proportion. Since black is me tall, then it easily and firmly fuses with the basesmetal of the object.

Enamelis a special alloy of vitreous mass sy, painted in different colors by metal oxides fishing After firing, it turns into a solid gloss pulling mass with stable, bright colors.

Masters used:

tin oxide - white;

iron oxide - yellow and aquamarine;

copper oxide - turquoise;

magnesia - purple;

gold - red;

iridium - steel, gray, black;

uranium and silver oxide - yellow.

Enamels are cloisonne, notched,carving (engraving), casting, scanned hornmentu (or in scanned frames), according to the chased cast or embossed, transparent(window), picturesque (painted) and irrigation(on a smooth surface).

Enamel is best placed on gold. Gold melts at high temperature, enamelthe mass does not oxidize and holds firmly. to silverre used more fusible enamels.

cloisonne enamel - this is enamel enclosed in cells formed by thin metal strips soldered on the edge to the me talus object, mainly to gold.

Enamel champlevé, casting, carving (engraving rovke) -the technique is much simpler than enamelpartitioned. The drawing is deeply removed (you cut) in the thickness of the metal, and the resulting in reAs a result, the recess is filled with enamel, afterwhich the object is fired and then polished ut.

Enamel on the removed ornament (in scanned frames)- widely used in Russia withXVI century. Distinctive features: made without counter-enamel and not polished.

Relief enamel - transmits volumetric messagestic forms. The most sophisticated techniqueof the highest skill.

Enamel transparent (window) - this technical cue technique requires great skill and carefullysti at work. Clear enamel decoratesobjects made of filigree (openwork) or sawn intometal. She did not receive a wide race in Russiaspace. Found only in items XIX - XX centuries.

Painted enamel - thing isgold or copper plate (or object) according tocovered with a layer of monochromatic enamel and fired. This background is applied with a brush with special enamelmi paints with essential oils ornament orimage and then fired.