Gemstones: classification, extraction and types of cutting

Gems have accompanied humanity throughout its history. Their origin and growth in the bowels of the Earth is a great mystery. Their extraction and finishing is a huge work. They are accompanied by legends, rumors, and often crimes. There are many ambiguities in their history. But they are immortal, as well as man's craving for beauty.

Gemstones of mineral origin are transparent, colorless or colored in a solid blue, green or red color. They are made precious by their rarity, difficulty of extraction and processing, high hardness and transparency. it diamonds, emeralds, sapphires, rubies... Organic gemstones include pearl, which originates and grows in the shells of molluscs.

Both mineral and organic gemstones are highly resistant to wear and tear. When properly stored and cared for, they retain their color and shine for centuries. They are also resistant to the effects of chemically active substances (acids and alkalis). Gemstones are 1st order gemstones. They are placed in frames made of precious metals. The most expensive jewelry is made of them. Their purchase is not only the acquisition of a beautiful thing, but also a reliable investment of money, a recognized bank asset.

Mining for gemstones is complex and costly. Deposits are scattered all over the world, many of them are located in hard-to-reach places with unsuitable natural conditions for life. Minerals are buried deep in the ground, and their extraction requires a lot of labor. This is an essential component of the high price of jewelry.

Any work on the extraction of precious stones begins with geological exploration. In places of probable deposits, test drilling is carried out, diagnostic pits are dug. These places are most often determined by the emergence of "rocks" on the surface, where people periodically find beautiful transparent nugget stones.

1. Placers... These are the places where valuable rocks come out to the surface of the earth. The stones are mined by hand washing in special trays.

2. Mining... They dig a mine and extract stones by hand.

3. Open careers... This is an industrial mining method. Huge stepped excavations in the ground where excavators and mining trucks are operating.

Technological progress has had little impact on the methods of mining precious stones.

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

The hardest and most transparent of all gemstones. Ideally, colorless (these are more expensive), but there are also blue, green, pink shades. These colors of diamonds are called fancy. They talk about some defect in the crystal lattice of the mineral, in which carbon atoms are replaced by other elements. These diamonds are cheaper, but more distinctive.

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

Belongs to the group of beryls - aluminum and beryllium silicates. Green and dark green color is given to it by compounds of chromium, vanadium or iron. They retain their color even under 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 are 5-6 carats, bright green, without foreign inclusions, perfectly transparent. They can cost more than diamonds of the same size, but this is rare.

It belongs to the corundum group. Corundums are aluminum oxides. Mostly used in industry as abrasives. Jewelry corundum - ruby ​​(red) and sapphire (blue).

Rubies with an asterism effect are also highly valued. When light falls on the surface of the stone, a star-shaped flare is formed. This is due to the inclusion of rutin crystals in the ruby.

The red color of the ruby ​​is given by chromium oxides. The color can be of different depths and density - from pale pink to dark red. Since ancient times, color symbolized blood, and the ruby ​​was associated with passion, love, courage. The ancient Russian name for ruby ​​is yakhont.

Ruby deposits are located in South Asia, Central Africa. In Russia, rubies are mined in the Northern Urals. High-quality and pure rubies can rival diamonds in value. But it strongly depends on the market and auction conditions.

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

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

Alexandrite is sometimes included in the list of precious stones. According to the main descriptions, it is geologically close to the emerald, but is capable of changing color depending on the lighting. But among scientists there is no consensus regarding its value. It is rather a rare semi-precious stone.

Organic stone. Formed in the body of bivalve molluscs. It is considered the most ancient precious piece of jewelry. It does not require additional processing, since the pearls initially have the correct shape - oblong or spherical.

Growing a pearl is a mollusk's defensive reaction to a grain of sand or other irritating particle trapped in the shell. The mollusk envelops a grain of sand with crystals of calcium carbonate. A pearl grows to the size of a pea in 12 years.

The color of pearls can be white, yellow, red, gray, black. The list of colors is not complete; 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 widespread in the north of Russia. Both the festive attire of ordinary people and the vestments of statesmen and clergymen were decorated with pearls.

Historically, there are two main ways of working with gemstones. These are tumbling and cutting.

Tumbling - this is grinding and polishing stones in a special tumbling drum. As a result, stones are obtained with a streamlined dome-shaped shape, without edges. Minerals processed in this way are called cabochons. Tumbling is mainly applied to semi-precious translucent and opaque stones, but sometimes rubies and sapphires are processed in this way to emphasize some of the subtleties of the play of light (asterism, for example).

Cut - This is giving natural minerals the shape of polyhedrons. Technically much more difficult than tumbling. It became fully accessible with the development of technology and the appearance of abrasive materials of sufficient hardness. Facets (or facets) are geometrically correct areas on the surface of a stone; they give it grace and a special inner glow.

There are several classic gemstone cuts.

This is the most common and most versatile cut. It is used for any kind of decoration. As a rule, a processed large stone has 57 facets. Smaller stones are simplified into 33 or 17 facets. A stone cut in this way is visible clearly and contrastingly, its surface is maximally open to light. An essential feature of this type of cut is the large weight loss of the original stone.

A variety of round cut stones for necklaces, pendants, bracelets. The area of ​​the facets 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 faces. This cut is considered "aristocratic", refined taste.

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

Rectangular cut. Up to 68 faces. It is especially popular in the manufacture of rings. Non-rounded corners are quite fragile and need a solid frame.

Rectangular cut with rounded corners. 57, 65 and more facets depending on the size of the stone. For such a faceting, large and clean stones are taken. Used in any jewelry. Minerals processed in this way give a bright flash when the light incident on them is refracted.

Square cut, similar to Emerald, but with more tier facets. It 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 for processing. Jewelry with stones of this cut is impressive and rich. Like Asher, it is often used in men's rings. 65, 70 and more faces.

Decorative or, as experts say, a fancy cut. Very good for pendants and pendants. Assumes a fairly large stone. 57-58 faces. The processing technique is similar to the pear-shaped cut. Craftsmen try to maintain the same longitudinal and transverse dimensions of the stone after processing. This guarantees visual line harmony and strength.

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

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

There are four main criteria for evaluating: color, clarity, weight, quality of processing.

The assessment of value by color fully applies only to diamonds, because the most valuable of them are considered colorless, while others have a very narrow color scale due to their complete transparency. Evaluation of other precious stones - rubies, emeralds, sapphires, is very difficult due to subjective factors and well-established beliefs.

However, some generally accepted criteria do 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 a stone. Natural defects - cracks, opacity, structural irregularities, foreign inclusions affect the color, gloss, quality of the finish. If these defects are obvious and pronounced, then this significantly reduces the price of the mineral. The share of purity in the final price of a gemstone ranges from 30 to 50%.

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

They are the most important characteristics in the appraisal of a gemstone. The weight of the stone and its price are in direct proportion. For precious stones, a special unit of mass is adopted - carat (ct), equal to 0.2 g or 200 mg. The stones are weighed on a special high precision jewelry balance. The larger and heavier the stone, the higher the price per carat of its weight.

In Russia, the most popular diamonds weighing about 0.1 carats. Jewelers call them "folk" and estimate approximately at 10 thousand rubles. A half-carat diamond will cost approximately 170-180 thousand, and a 1-carat diamond will cost about 500 thousand rubles. But prices fluctuate greatly depending on the characteristics and qualities of specific stones.

Extraordinary, magical, healing properties have long been attributed to precious stones. Diamond - a symbol of perfection, strength, inflexibility. Protects the owner from evil spells. Ancient healers believed that the diamond spreads certain waves that have a beneficial effect on the human heart and brain. Emerald personifies wisdom, calmness, protects from witchcraft, damage, evil eye. Normalizes blood pressure. Ruby has a 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 maintain kindness and integrity of the soul. Healers believe that sapphire protects a person from colds, tumors, and nervous disorders.

Pearl calms the psyche, prolongs life, rejuvenates the body. Pearl products protect the digestive tract, kidneys, and liver from diseases. They normalize blood pressure, treat nervous disorders. In contact with human skin, pearls gradually change color and can serve as an indicator of beginning chronic diseases. In ancient times, in some countries it was considered an indicator of poisons. The pearl was thrown into a bowl of wine, and its color changed if the wine was poisoned.

Astrologers are also not indifferent to precious stones. 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 encouraged to wear diamond jewelry. Emerald, according to venerable astrologers, is most suitable for Pisces and Cancers, ruby ​​for Leo, and sapphire for Sagittarius. Pearls are highly recommended for Cancers, Pisces, Aquarius.

Gemstones have their own history and even legends. One of these - diamond "Koh-i-noor"... Its history can be traced back to 1300. Originally belonged to the rajas of the Indian principality of Malwa. Then, in the course of civil strife, he passed from hand to hand for a long time, until he was in the possession of the Great Mughals. Then he ended up in Persia, in Afghanistan, returned to India, where he was captured by the British and taken to London. It is stored there to this day, having survived a re-cutting in 1852 and lost more than 40 percent of its mass. Initially, it weighed 191 carats, and after re-cutting - 108.9 carats. The re-cutting gave the tarnished rarity brightness and transparency.

"Orlov" - a large diamondfound in India at the beginning of the 17th century. Weighs 199.6 carats. It belonged first to Indian rajas, then to the Great Moguls. It disappeared in the middle of the 18th century. Most likely, he was kidnapped and taken to Europe. The diamond ended up in Russia in the 70s of the 18th century. Legend has it that it was presented to Empress Catherine II by her favorite Grigory Orlov. However, historians claim that Orlov could not pay 400 thousand rubles for the stone, he simply did not have that kind of money. It is more likely that the empress herself acquired the diamond at the expense of the treasury, and in order to hide this, she asked Orlov to stage a gift, which he did. The diamond was named "Eagles" and was inserted into the pommel of the imperial scepter. Stored in the Diamond Fund of Russia.

Chinese and Indians idolized pearl... Finding a pearl was considered a great success and a good sign. According to one of the Chinese legends, once two dragons fought in the sky. Clouds were gathering, lightning flashed dazzlingly, and terrible thunder roared. At the sharpest moment of the thunderstorm, it rained pearls. The upheavals ended and peaceful calm times came. The Indians believed that pearls were the first raindrops that fell into the sea. The shells rise from the bottom, open the flaps and catch these drops. This is how pearls are formed.

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