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Read More Gemstone Properties Gemstone Clarity Gemstone Color Gemstone Form Gemstone Crystal System Gemstone Color Chart Specific Gravity Luster Cleavage Continue Reading about Gemstone Agate Amber Calcite Diamond Emerald Garnet |
Another case is rarity of color. A good example is emerald, the deep green variety of the mineral beryl. Beryl occurs throughout the world, usually found in pegmatites. Emerald owes its green color to the element chromium. Chromium, however, is not usually present in
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pegmatites. Its geochemical environment is rather in dark-colored (basic) igneous rocks. Beryl is rarely found in these latter geologic environments, largely because its primary constituent, beryllium, is rare in basic rocks. The conditions necessary for the occurrence of emerald, i.e., the formation of beryl plus the availability of chromium, are thus seen to be mutually incompatible! This accounts for the worldwide paucity of emerald. The reasons become obvious when one understands the geologic factors.
Finally, there is scarcity in size. Topaz, for example, occurs in crystals that weigh hundreds of pounds. These are usually colorless or very pale yellow or blue. But topaz crystals of a fine pink color are never seen in sizes larger than a few inches. A huge |
faceted gem of white topaz is not rare, but a 10 carat pink topaz would be. Likewise, rubies of very fine quality (color and transparency) are extremely rare over about 10 carats. But sapphires, which are mineralogically equivalent to ruby (both are the mineral corundum), are encountered in crystals weighing hundreds of carats.
Large amethyst crystals are found in many localities. However, pieces free of inclusions weighing more than 50 carats are quite rare. In general, it is clear that rarity is a combination of a number of factors, all of which depend on the basic geology of a gemstone species plus the status of the
marketplace. Scarcity is a function of the following factors: geologic abundance of the species in question; desirable color, size, and freedom from imperfections; market availability (number of producing localities and the sizes of the deposits); demands of the market.
A gemstone occurrence is a very rare and transient geologic feature. Once exhausted, it cannot be replenished within the span of human lifetimes. Synthetics can be manufactured in the laboratory, but the value of natural gemstones will not be affected as long as they can be distinguished as rare natural objects of great beauty.
The gemstone market is continually faced with the threat of depletion of known gemstone deposits, or loss of production due to political factors. This puts great pressure on other known sources to meet world demand. Depletion of supply coupled with high demand creates rising prices. This is a major reason why gemstones have had great appeal throughout history as an investment medium and a way of storing wealth. Gems are what might be called "real value" commodities, with desirability in all cultures, throughout all the periods of human history.
Geological scarcity accounts for such rare gemstones as painite and taaffeite. Only one painite crystal has been found, and less than half a dozen cut taaffeites are known. To be sure, more specimens of both materials may exist; painite may resemble ruby and taaffeite looks like mauve spinel, and misidentified cut stones may exist in various collections and inventories. Nonetheless, such rare collector gems offer a situation comparable to art. Rembrandt is dead, and no additional original Rembrandts can be produced. By analogy, an exhausted gem deposit can produce no more gemstones.
marketplace. Scarcity is a function of the following factors: geologic abundance of the species in question; desirable color, size, and freedom from imperfections; market availability (number of producing localities and the sizes of the deposits); demands of the market.
A gemstone occurrence is a very rare and transient geologic feature. Once exhausted, it cannot be replenished within the span of human lifetimes. Synthetics can be manufactured in the laboratory, but the value of natural gemstones will not be affected as long as they can be distinguished as rare natural objects of great beauty.
The gemstone market is continually faced with the threat of depletion of known gemstone deposits, or loss of production due to political factors. This puts great pressure on other known sources to meet world demand. Depletion of supply coupled with high demand creates rising prices. This is a major reason why gemstones have had great appeal throughout history as an investment medium and a way of storing wealth. Gems are what might be called "real value" commodities, with desirability in all cultures, throughout all the periods of human history.
Geological scarcity accounts for such rare gemstones as painite and taaffeite. Only one painite crystal has been found, and less than half a dozen cut taaffeites are known. To be sure, more specimens of both materials may exist; painite may resemble ruby and taaffeite looks like mauve spinel, and misidentified cut stones may exist in various collections and inventories. Nonetheless, such rare collector gems offer a situation comparable to art. Rembrandt is dead, and no additional original Rembrandts can be produced. By analogy, an exhausted gem deposit can produce no more gemstones.
References:
1- Color Encyclopedia of Gemstones, Joel E. Arem, VNR publications, New York.
1- Color Encyclopedia of Gemstones, Joel E. Arem, VNR publications, New York.