Almost all gemstones are minerals with a crystalline structure. However, some gems are not really gemstones. Rather their origin is organic. This means that they formed from biological processes, whether animal or vegetable.
Amber is the fossilized hardened resin of the pine tree, formed approximately 50 million years ago. Amber has been used since prehistoric times for jewelry, amulets and religious objects. The most prized pieces contain inclusions of insects, plants or pyrite. The largest amber deposits in the world are near Kaliningrad, Russia, and there are large reserves in the seabed of the Baltic.
Coral is a branching, skeletal structure built by small marine animals known as coral polyps. Gem-quality coral is related to reef-forming corals, and the most valuable coral variety is found in the Mediterranean, the Red Sea and in coastal Japan. Colors can be bright to dark-red, orange-red, orange-pink, pink, white, blue or black. Unworked coral is dull, but when polished it exhibits an attractive vitreous luster.
Jet was extremely popular in the 19th century, but now is rarely found. Jet is actually bituminous coal that can be polished. It was made famous by Queen Victoria of England, who wore jet as part of her mourning dress after the death of Prince Albert. Jet is extremely light and long necklaces of jet beads were very popular during the 1920s when women wore several long strands of jet beads, stretching from the neck to the waist.
Ivory originally referred to the material that makes up elephant tusks. Today, ivory also comes from the teeth of hippopotamuses, walruses, wild boars and other mammals. Like bones, ivory consists mainly of calcium phosphate. Before the invention of plastic, ivory was important in the manufacture of cutlery handles, musical instruments, billiard balls and many other ornamental carved objects. Due to the rapid decline in the populations of the animals that produce it, importing and selling ivory is banned or severely restricted in many countries.
Pearls are the most important of all the organic gems. Grown or cultivated in bivalve mollusks, pearls have been used for adornment for more than 6,000 years. By 2500 B.C. there was already a substantial pearl trade in China. One of the unique features of pearls is that they do not require any processing - they exhibit an attractive pearly luster in their natural state.
- Prima Pubblicazione: May-29-2008
- Ultima modifica: December-18-2019
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