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Home Precious stones Demantoid


gemantoidDemantoid, or green garnet (andradite) is a green crystal (Ca3Fe2(SiO4)3), the softest of the garnets, with a Moh’s hardness of 6.5-7. Its coloring varies from almost colorless to yellow-green, but the most valuable is the rich, bright-green color. The best samples of this stone are mined in Russia.

Green garnet from Russia sells well in North America, Great Britain, Japan, and Hong Kong. Demantoid is also mined in Italy, the U.S., Mexico, Namibia, and Iran, but those stones are not even near what Russia has, most likely because the Urals are so old. Centuries ago, these mountains were high and rocky like the Himalayas, but over hundreds of millions years, they lost their majestic shape and now look more like rounded hills. All native deposits of gemstones in the Urals eroded a long time ago. Scientists believe that there are large deposits of demantoid in the Caucasus, the Alps, and the Himalayas, but these mountain systems are too old; to see the placement of shiny crystals like demantoid, we would have to wait for about 10 million or so years, when the water and wind have done their job with erosion.

Demantoid was discoverd not so long ago--in the middle of 19th century--on the Bobrovka River in the Urals. That is why in Russia it was often called “Bobrovka garnet” or “Ural emerald,” and in the West, it was “Siberian chrysolites.” Later, the deposits of demantoid were discovered on the Kamchatka.

Sometimes, geologists find spots where, according to all characteristics, the native bodies of deposits have been formed, but the raw material is actually rare there. Everything is washed away by the rivers and the rains, which mean large quantities of demantoid are settled in the ancient river whirlpools and sloughs; this is called the alluvial process. Quite often, those who do not know the basics of geology start digging in where there are lots of stones on the surface, believing the deeper you get, the more stones you are going to find. But nothing is as simple as it seems. Lots of cases are known when the miners tried to uncover the alleged deposits, digging deeper and deeper, but they were, in fact, only losing time and money.

‘Horse tail’ in a crystal (magnified)‘Horse tail’ in a crystal (magnified) gemantoid_01 In a sapphire mountingIn a sapphire mounting

It is a lot easier to mine gemstones in the tropical countries, where there are also many alluvial deposits. Mountains there are young, but they are washed away much faster, taken only a few dozen million years. The prolonged rainy season with its frequent storms does its job well; when the rain or storm is over, crowds in Myanmar go after the stones brought to the surface by the weather, and very few people leave without at least stone or two. One must agree that this is a much easier method than digding the layers of alluvium. In Russia, on the contrary, the mountains are protected by snow during the long winters, so despite its age, the Urals are washed away very slowly.

The Ural deposits are not mapped, and the territory where one may find something is quite large, so the “Bobrovka garnet” brought forth a system of unwritten rules that are, as you can imagine, quite hard to understand. Here, it is totally unacceptable to ask questions, because you will only raise suspicion. In the obscure land, where the local authorities and the militia also play a role, year after year, many locals prowl through the mountains trying to find a beautiful stone with the hope of selling it to support their families. But even if they find something really valuable, they get almost nothing for it; according to the laws, one must give all such findings to the state on the percentage basis. But as the free miners do their search outside the legal field, they are subject to intimidation and harassment by others. Nobody defends them, so the major part of the profit “settles” in the pockets of a multilevel system of intermediary buyers.

Therefore, those who want to buy a demantoid will have to deal with the highest level of this crime organization. It is very difficult to come to an agreement with those people, and when they finally do agree to sell you something, new players suddenly appear on the stage. The exits from deposits are guarded by militia, which sets ambushes and searches the cars. They always have surprisingly exact information about who is carrying what, as well as where you are going. It suggests some not very pleasant things, including the idea that those who sell the stones could also be selling information to the militia. Of course, the guardians of law and order are far from killing the goose that lays the golden eggs, so it is always possible to negotiate some agreement with them. The sum of this “agreement” is usually included in the price of the stone.

Some companies get licenses for exploration and production of demantoid. But they also have their share of backdoor war with the participation – this time – of Gosprirodnadzor and Okhranpriroda. Among the hired miners, there are many who come from Tajikistan and other former Soviet republics. They use mainly spades, pickaxes, and stretchers. Those workers hide stones from the management at every step, always trying to get the biggest and the most valuable. The intermediaries take up their residence nearby and play the tourists and vacationers who came to admire the beauty of local nature. Sverdlovskaya and Chelyabinskaya oblasts are all in for this profitable business game, one which then goes on to the international jewelry fairs in Tucson, Denver, Bangkok, Vicenze, Basel, and Hong Kong.

gemantoid_04 Demantoid insectDemantoid insect gemantoid_06

To base a serious business on demantoid in such conditions is extremely difficult, but conditions are difficult all over, not just in Russia; it is the problem of all alluvial deposits in the world. Such deposits cannot be controlled by anybody; not the state, not the private business, and not even the mafia. However, they all try hard to succeed in this field. Anywhere one finds an alluvial deposit can also find some shady things happening…

Demantoid, like many other gemstones, is given temperature treatment and has been treated this way even in the 19th century, when they lit bonfires, with a temperature that cannot exceed 760°, in the graphite powder. It is highly possible that iron in demantoid changes its chemical valency, which is reflected in the coloring of the mineral. Only the Bobrovka stones are not subject to such burning; Russian demantoids could be somewhat opaque, or contain inclusions, but it is, probably, the only gemstone in the world with the “horsetail” or “sun” inclusion that gives it even more value. Stones of particular value are those with the rays of the “tail” moving symmetrically up from the lowest point and separating by the table of the cut crystal. This effect gives an absolutely fantastic play and shine to the stone. A side note: if you look at a horsetail inclusion through a magnifier and see the threads interrupted, it is clear that the stone was heated, so the price should be lower.

Earlier, only four types of demantoid were recognized, but now that number has risen to 11. There are three types of color: golden, silver, and reddish. But the best color is a rich green with a slight blue touch. The price of such stones, which should be transparent, rises geometrically and depends on its size.

A demantoid’s market price is set as follows: round cut stone, diameter 2mm (0.02 carats) – $350; 3 mm (0.25 carats) – $450; 4 mm (0.5 carats) – $600; 5 mm (1 carat) – $1000; as for a five-carat gem, it can easily cost $10,000 per carat. Stones over 10 carats are extremely rare, but their color saturation is inferior to their smaller “brothers.” The largest demantoid in the world was found in the Urals, and it weighs 252.5 carats (50.5 g).

The name of the stone comes from Dutch demant (diamond) and Greek eidos (alike), which is quite understandable, as demantoid’s dispersion is the second highest among the precious stones, after diamonds. Demantoids can shine even in the dark. This is why it is preferable to show it in a dim light, because the stone looks even more beautiful. A demantoid shines all the rainbow colors, and as for the light deflection, it beats even diamonds. This is the reason that Carl Faberge loved demantoid so much and used it for many of his famous pieces of jewelry. Kuprin’s short story “The Garnet Bracelet” tells us about demantoid’s popularity during his time. Today, many owners of this truly unique precious stone exchange their old demantoids for newer ones as the choice now is much wider than 100 years ago, making it possible to pick up better stones.