There is a kind of precious stones but the number of less important, but actually they are not little rock. They must be the Crystal structure of minerals, precious stones of organic origin of this-they are created from the biological process, be it in animals or plants. The number of gemstones is small but has great diversity, are important in the trade of gems: amber, coral, charcoal, ivory and pearls.
Coral is a type of structure the skeleton branches is formed from the small sea animals called coral polyps. Coral gemstone quality is related to the species of coral reefs forming, but the kind most precious coral was discovered in the Mediterranean Sea, the Red Sea and the sea of Japan Coast. red light from color to dark red to orange-red, Orange, pink, red, white, green and black. The coral have yet to handle very rough, but when they will be bright as the mirror balls are very attractive.
Red coral species of coral grow on rocky sea fish, usually in a dark environment or in deep or in burrows. Coral branches include the element calcium carbonate hardness, was created by color carotnoid color array. Red corals often have dark reddish pink lined from Pink salmon to dark red, from coral (Coral) also refers to the name of that color. However, coral gemstone quality are also found in the white, black and green.
Because the colour durability and bold and sparkling, coral branches be exploited from time immemorial with decorative purposes. Jewelry by
corals have also been discovered in the tombs of ancient Europe and the history of ancient Egypt. The most precious coral species is exploited in the Mediterranean Sea, particularly in Sardinia. They have also been found in the Pacific Ocean, in Japan, Taiwan and Australia. (Vietnam also have few species).
Because the corals are of organic origin, it is not particularly durable. It’s also hard enough, but not by the other gemstones. It’s just been folded from 3 to 4 in the Mohs. Coral under the influence of heat, acid, hot fluids, and color can be faded when used. Coral red and white has the specific gravity or density of around 2.6-2.7 and refractive index 1.486-1.658. Coral from transparent to opaque white.
Polished with coral grained sandstone and abrasive powder, then polished with felt. It is used to do the particles in the grain chain or bracelet, jewel encrusted objects or circular, grinding.