Precious stones: classification, mining and types of cut

Precious stones accompany humanity throughout its history. Their origin and growth in the bowels of the Earth is a great mystery. Their mining and finishing is a great job. They are accompanied by legends, rumors, and often crimes. There are many ambiguities in their history. But they are immortal, as well as the craving of man for the beautiful.

Precious stones of mineral origin are transparent, colorless, or monochromatic blue, green or red. They are made precious by rarity, difficulty of extraction and processing, high hardness and transparency. it diamonds, emeralds, sapphires, rubies. Organic gems include pearlswhich originates and grows in the shells of mollusks.

Both mineral and organic gems are very resistant to wear. With proper storage and good care, they retain color and shine for centuries. They are resistant to the effects of chemically active substances (acids and alkalis). Gems are jewelry of the 1st order. They are placed in frames of precious metals. Of these, the most expensive decorations are made. Their purchase is not only the acquisition of a beautiful thing, but also a safe investment, a recognized banking asset.

Gem mining is a complex and expensive business. Deposits are scattered around the world, many of them are in remote places with little suitable for life natural conditions. Minerals are buried deep in the earth, their extraction requires large labor costs. This is a significant component of the high price of jewelry.

Any work on the extraction of precious stones begins with geological exploration. In the field of probable fields, test drilling is being carried out, and diagnostic holes are being dug. These places are determined most often by the emergence of a “rock” to the surface, where people periodically find beautiful transparent nugget stones.

1. Placers. These are the places where the valuable species reach the surface of the earth. Stones are mined by hand washing in special trays.

2. Mine workings. Dig a mine and mine stones by manual labor.

3. Open careers. This is an industrial mining method. Huge stepped grooves in the ground where excavators and mining trucks operate.

Technical progress had little impact on the way gems were mined.

Natural or "wild" sea pearls mined in the sea by fishing. Divers pull from the seabed shell with pearls. This is a centuries-old trade, associated with the constant risk to life. At the end of the 19th century, the method of cultivating pearls in artificial conditions was discovered. An irritant, the nucleus of the future pearl, is implanted into the shell, and grown on special farms. This method allows you to get cheaper pearls in large quantities.

The hardest and transparent of all gems. Ideally colorless (such are more expensive), but there are also blue, green, pink shades. These colors of diamonds are called fantasy.They speak of a certain defect in the crystal lattice of the mineral, in which carbon atoms are replaced by other elements. Such diamonds are cheaper, but more distinctive.

The main physical characteristic of a diamond is hardness. He has the highest score (10) on the Mohs scale. It is an octahedral carbon crystal, which appeared at ultrahigh pressure and temperature during the intensified volcanic activity of the Earth. Only 1/5 of the mined diamonds are used to make jewelry. 80% used in industry. The main deposits are located in Australia, South Africa, India, Brazil. In Russia, most diamonds are mined in Yakutia.

Belongs to the group of beryl - aluminum silicate and beryllium. Green and dark green color give it compounds of chromium, vanadium or iron. They retain color and artificial light. They are mined in Colombia, USA, Australia, South Africa. In Russia, large deposits of emeralds are located in the Urals. The most valuable stones in 5-6 carats, bright green, without extraneous inclusions, perfectly transparent. They may cost more than diamonds of the same size, but this is rare.

It belongs to the group of corundum. Corundum - aluminum oxide. Used mostly in industry as abrasives. Jewelry corundums are ruby ​​(red) and sapphire (blue).

Also expensive are rubies with the effect of asterism. When light falls on the surface of the stone, a star-like flare is formed. This is due to the incorporation of rutin crystals into ruby.

Chromium oxide gives red to ruby. Color can be of different depths and thicknesses - from pale pink to dark red. Since ancient times, color has symbolized blood, and the ruby ​​has been associated with passion, love, courage. The old Russian name for ruby ​​is a yacht.

Ruby deposits are located in South Asia, Central Africa. In Russia, rubies are mined in the Northern Urals. High-quality and pure rubies can compete with diamonds for value. But it is highly dependent on market and auction conditions.

Mineral with predominant shades of blue. From the group of jewelry corundum. Titanium and iron compounds give it a blue color.

Sapphires are mined in Australia, South Asia, and Central Africa. In Russia, a large deposit of sapphires is located in Primorye.

To the list of gems sometimes also alexritrite is included. According to the main descriptions, it is geologically close to emerald, but it can change color depending on the lighting. But among scientists there is no consensus regarding his jewels. It is rather a rare semi-precious stone.

Stone of organic origin. Formed in the body of bivalve mollusks. It is considered the most ancient precious ornament. It does not require additional processing, as the pearls initially have the correct form - oblong or spherical.

Growing a pearl is a defensive reaction of a mollusk to a grain of sand that has entered the shell or another irritating particle. The mollusk envelops a grain of sand with calcium carbonate crystals. To the size of a pea pearl grows in 12 years.

The color of pearls can be white, yellow, red, gray, black. The list of colors is incomplete, different shades are possible. Natural pearls are currently mined in the Red Sea and the Persian Gulf. An ornamental variety is freshwater pearls. It is mined in rivers. This craft was distributed in the north of Russia. Pearls were decorated with holiday dresses of ordinary people, as well as vestments of statesmen and clergymen.

Historically there are two main ways to process precious stones. This is tumbling and faceting.

Tumbling - it is grinding and polishing stones in a special tumbling drum. The result is a streamlined dome-shaped stones, without edges. The minerals treated in this way are called cabochon. Tumbling is applied mainly to semi-precious translucent and opaque stones, but sometimes rubies and sapphires are treated with this method in order to emphasize some subtleties of the play of light (asterism, for example).

Cut - It is giving the natural minerals the shape of polyhedra. Technically much more difficult tumbling. Became fully accessible with the development of technology and the appearance of abrasive materials of sufficient hardness. The edges (or facets) are geometrically correct platforms on the surface of the stone, they give it elegance and a special inner radiance.

There are several classic types of gem cutting.

This is the most common and most versatile type of cut. It is used for any jewelry. The processed large stone has, as a rule, 57 facets. Smaller stones are subjected to a simplified faceting of 33 or 17 faces. The stone cut in such a way is clearly visible and contrasting, its surface is as open as possible to light. A significant feature of this type of cut is a large weight loss of the original stone.

A variety of round cut stones for necklaces, pendants, bracelets. The area of ​​the faces is larger than with a round cut. There are 57 of them.

Oval cut with pointed ends. It is used in rings, earrings, pendants. 55 facets. Such a cut is considered “aristocratic”, refined taste.

Combines the features of 55-56 faces. Ideal for pendants, earrings, necklaces.

Rectangular cut. Up to 68 facets. Especially popular in the manufacture of rings. Non-rounded corners are quite fragile and they need a reliable frame.

Rectangular cut with rounded corners. 57, 65 and more faces depending on the size of the stone. For such a cut, large and clean stones are taken. Used in any decorations. The minerals treated in this way give a bright flash when the light incident on them is refracted.

Square cut, similar to Emerald, but with a large number of tier faces. Can have up to 72 faces. This type of cut is very popular in men's rings.

A stone of perfect purity and without damage is taken into processing. Jewels with stones of such a cut are impressive and rich. Like "Usher", it is often used in men's rings. 65, 70 and more faces.

Decorative or, as experts say, a fantasy cut. Very good for pendants and pendants. It assumes a fairly large stone. 57-58 facets. The processing technique is similar to a pear-shaped cut. Masters try to maintain the same longitudinal and transverse size of the stone after processing. This ensures visual harmony of lines and durability.

Equilateral triangle. May have from 19 to 52 or more faces. The configuration of the faces depends on both the size of the stone and the creative idea of ​​the master.

These are the main types of gem cutting. There are other, more complex. With the development of processing technologies for solid materials, we should expect new discoveries in jewelry.

There are four main evaluation criteria: color, purity, weight, quality of processing.

Valuation by color is fully applicable only to diamonds, because the most valuable of them are considered colorless, while others have a very narrow color scale due to full transparency. Evaluation of other precious stones - rubies, emeralds, sapphires, is very difficult due to subjective factors and well-established ideas.

However, some generally accepted criteria still exist.This is the uniformity of color, its saturation and solidity. A stone with these qualities to a greater extent, as a rule, is valued much higher.

One of the most important components of the price of stone. Natural defects - cracks, opacities, structural irregularities, foreign inclusions affect color, brilliance, quality of finish. If these defects are clear and pronounced, then this significantly reduces the price of the mineral. The share of purity in the final price of the gem is from 30 to 50%.

A very important aspect in terms of aesthetic perception of a gemstone. Expensive decoration should not just be beautiful, it should delight. Special, individual for each stone techniques and secrets of granilers allow us to fully experience the play of light, the saturation and the depth of the color of the mineral. In the world there are several classifications of cut quality. This is necessary because expensive products usually have a special certificate, which indicates the main characteristics. Russian classification of cut quality is considered one of the most accurate. It accepts letters. A (first-class cut), B (good), C (medium) and D (bad). The cut quality index is one of the most important criteria for evaluating a stone.

Are the most important characteristics in the evaluation of precious stones. The weight of the stone and its price are in direct proportion. For gems, a special unit of mass is used - carat (ct), equal to 0.2 g or 200 mg. Stones are weighed on special high precision jewelry scales. The larger and heavier the stone, the higher the price of a carat of its weight.

Diamonds weighing about 0.1 carats are the most popular in Russia. Jewelers call them "folk" and estimate approximately 10 thousand rubles. A half-carat diamond will cost approximately 170-180 thousand, and one carat will cost about 500 thousand rubles. But prices vary greatly depending on the characteristics and qualities of concrete stones.

Gemstones have long been attributed to extraordinary, magical, healing properties. Diamond - a symbol of excellence, strength, intransigence. Protects the owner from evil spells. Ancient healers believed that the diamond spreads some waves that are beneficial to the heart and brain of man. Emerald personifies wisdom, tranquility, protects from witchcraft, damage, the evil eye. Normalizes blood pressure. Ruby beneficial effect on the brain and heart. Improves memory. Prevents diseases of the spine and joints. Strengthens the nervous system.

Sapphire - a symbol of wisdom, power, justice. Indian priests attributed a special vital energy to sapphire and believed that it helps a person to maintain the goodness and integrity of the soul. Healers believe that sapphire protects a person from colds, tumors, and nervous disorders.

Pearls calms the psyche, prolongs life, rejuvenates the body. Products made from pearls protect against the diseases of the digestive tract, kidneys, and liver. Normalize blood pressure, treat nervous disorders. In contact with human skin, pearls gradually change color and can serve as an indicator of incipient chronic diseases. In antiquity in some countries was considered an indicator of poisons. The pearl was thrown into the wine cup, and its color changed if the wine was poisoned.

Are not indifferent to gems and astrologers. They believe that the diamond is the stone of the Sun and Venus, and its “favorite” signs are Aries, Sagittarius and Leo. People born under these signs are advised to wear diamond jewelry. Emerald, in the opinion of venerable astrologers, is most suitable for Pisces and Cancers, ruby ​​for Leoes, and sapphire for Strelets. Pearls are highly recommended for Cancers, Pisces, Aquarius.

Gems have their own history and even legends. One of these - diamond "Kohinur". Its history has been traced since 1300. Originally belonged to the rajas of the Malwa Indian Principality.Then, in the course of civil strife, it passed from hand to hand for a long time, until it was in possession of the Great Moguls. Then he ended up in Persia, in Afghanistan, returned to India, where he was captured by the British and taken to London. It is still kept there, having survived in recutting in 1852 and having lost more than 40 percent of its mass. Initially, he weighed 191 carats, and after recut - 108.9 carats. The recut gave the tarnished rare book brightness and transparency.

"Orlov" - a large diamondfound in India at the beginning of the seventeenth century. It weighs 199.6 carats. Belonged first to the Indian Rajas, then to the Great Moguls. In the middle of the XVIII century disappeared. Most likely, he was abducted and taken to Europe. In Russia, the diamond was in the 70s of the XVIII century. The legend says that it was presented to Empress Catherine II by her favorite Gregory Orlov. However, historians claim that Orlov could not pay 400 thousand rubles for a stone, he simply did not have that kind of money. It is more likely that the empress herself bought the diamond at the expense of the treasury, and to hide it, she asked Orlova to stage a gift, which he did. The diamond received the name "Eagles" and was inserted into the tops of the imperial scepter. Stored in the Diamond Fund of Russia.

The Chinese and Indians idolized pearls. Find a pearl was considered a great success and a good sign. According to one of the Chinese legends, two dragons once fought in the sky. Clouds were gathering, dazzling lightning flashed, terrible thunder thundered. In the most acute moment of a thunderstorm, it began to rain from pearls. The shocks ended and peaceful peaceful times came. The Indians believed that pearls are the first raindrops falling into the sea. Sinks rise from the bottom, open the doors and catch these drops. This is how pearls are formed.

In this video you can watch the extraction of precious stones in Vietnam.