Many green stones are used in jewellery, emerald being the best known of them. Some of the other favourites include green sapphire, demantoid, peridot, and chrysoprase.
Emerald is a transparent variety of beryl mineral with the hardness of 7.5 to 8 on the Mohs scale. Emeralds are very temperature-sensitive and lose their colour at 700 to 800 degrees centigrade.
In Russia, emerald circulation is regulated by the Federal Law 41-FZ “On precious metals and gemstones”.
In ancient times, emeralds were sourced at African deposits known as Cleopatra's Mines. South American Indians had been recovering emeralds long before they became known to the Europeans during La Conquista. Most deposits of Colombia and Brazil are still not exhausted. Most Colombian emeralds are special for their bluish green colour that has eventually become standard.
Today, the key emerald suppliers include Colombia, Zambia, Brazil, Afghanistan, Pakistan, Madagascar, Tanzania, and Russia. Each of the deposits in the countries has its own stone specifications, e.g. colour, quality, size, etc.
Emeralds vary in colour, and the shade is the key criterion used for evaluation of a gem. A perfect stone is free from visible cracks and inclusions. Cat’s eye emeralds and trapice emeralds with a pattern of rays are some of the rare types. (Trapice is in fact a wheel used to extract oil from sugar cane.)
Ancient Egyptians called emerald a gift of the great Toth God, and used it to decorate mummies and tombs. The stone was considered an emblem of eternal youth and the keeper of mothers-to-be; people believed it could turn dreams into reality, help to see the past and the future, and bring loyalty and love. In old times, emerald was worn as a powerful talisman, eye-healing and snake-repelling. In Russia, back in 15th to 17th centuries, it was honoured as a gem of wisdom and self-possession; Alexander Pushkin also appreciated his emerald ring for these exact qualities.
A well-cut emerald is found exciting by jewellers as well as poets, any artistic people and whoever wishes to touch upon eternity and the unity of times and generations. Octagon and Baguette are the two traditional forms of emerald cutting. Emeralds rich in inclusions are often cut en cabochon and used for intaglios featuring various foliage patterns. This cut was specifically popular back in 1930s and 1940s, when making Art Deco adornments.
The name comes from diamant (German for diamond) and eidos (Ancient Greek for alike) and means ‘diamond look-alike.’ Demantoid is a clear gem, a type of andradite, a mineral from the garnet group. Cat’s eye effect can be present in demantoids. Demantoids are very rare and valuable. At 6.5 on Mohs scale, they are not very hard.
Demantoids were first discovered in 1875 at the Bobrovka River close to Yekaterinburg, Russia. They were mined on the spot up to 1920 but then the mining faded. Today, Russia, Namibia, Kenya and Tanzania have known deposits of demantoids. Karkodinskoe deposit in the Middle Urals is currently the major supplier of jewellery quality demantoids to the global market.
Bright green demantoids are believed to bring calmness and peace, to help the owner stay focused and concentrated so he can use his knowledge as supposed, not wasting it around but channeling reasonably. Besides, demantoid is called a symbol of love and fertility.
Demantoid can display its colour better than even the diamond, hence brilliant cut as the most popular one for it (step and mixed cuts are also used). Some of the traditional shapes are Round, Oval, Pear and Marquis. Russian jewellers’ pieces to express Russian Art Nouveau style are of special value. Gold and enamel along with diamonds and other gems are perfect to highlight the beauty of a demantoid.
Peridot (chrysolite) is a clear variety of olivine, quite a fragile mineral at 6.5 to 7 on Mohs scale. It was once called evening emerald, its green hue becoming more intense and rich in twilight and specifically in the candle light. The unique peridot once owned by the Romanovs is now exhibited in the Diamond Fund and is one of its Seven Historic Stones. It has a rare, uniform olive green colour and is extremely clear despite its 5.2 x 3.5 x 1.05cm size and 192.75 carat weight. Some historians claim it is the ‘emerald’ that Nero used as a looking glass when watching gladiatorial fights, or maybe the Great Fire of Rome.
The most renowned deposit of peridots is found at the uninhabited island of Zeberged (St. John’s) in the Red Sea. Peridots are rare in Russia, mainly found in the diamond mines and beds in the north of Krasnoyarsk Territory and Yakutia. Jewellery quality peridots are discovered in Murmansk region, in the ores of Kovdorsky deposit. Other important peridot deposits are located in Pakistan, Arizona (USA), Australia, Brazil, Sri Lanka, Afghanistan, Egypt, Tanzania, and South Africa.
In ancient times, peridot was said to make its owner appealing to others. The gem had a reputation of protecting against nightmares and burns, and helping to sort out any problems. Peridot was the amulet of successful lawyers. In the Middles Ages, it was often owned by merchants and bankers, believed to protect belongings from fire and theft.
Peridot's hardness may vary depending on which direction you cut, thus it might be tricky to cut and facet, not all sides of it being easy to polish. Peridots are normally cut in steps; brilliant cut and cabochon are also used. The stone colour is often uneven, each stone having its individual structure pattern. A good jeweller always considers that when cutting.
Chrysoprase is a variety of quartz and chalcedony. It is often apple green; however, the colour can vary to deep green or bluish. Unlike many other frosty quartzes, chrysoprase is appreciated for its colour, not for its patterns or textures. Like other chalcedony forms, chrysoprase is rated at 6 to 7 on Mohs scale.
Chrysoprases are rare, mainly found in nickel-containing ores. The best deposits are in Australia, but the mineral can also be found in Germany, Poland, Kazakhstan, the Urals (Russia), USA, Brazil, India and Madagascar.
Chrysoprase is often referred to as the stone of luck, and has been used as a lucky charm since very long ago. Alexander the Great carried the gem at his belt, to be lucky in battle. Chrysoprase was considered protection against malediction and everything evil, and assistance in all endeavours. It helped to get rid of failure memories and open the heart for new love.
The noble colour of chrysoprase is best enhanced by en cabochon cutting. High, oval cabochons made of highest quality gems are specifically impressive. Chrysoprases are easily polished, but it can rarely be made truly ‘mirrorlike’.