Diamond :from the ancient Greek adámas “unbreakable”) Diamond has the highest hardness and thermal conductivity of any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools. Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers in the Earth’s mantle. Carbon-containing…
Emeralds are fascinating gemstones. They have the most beautiful, most intense and most radiant green that can possibly be imagined: emerald green. Inclusions are tolerated. In top quality, fine emeralds are even more valuable than diamonds. The name emerald comes from the Greek ‘smaragdos’ via the Old French ‘esmeralde’, and really just means ‘green gemstone’.…
Pearl is a hard object produced within the soft tissue of a living shelled mollusc. Just like the shell of a clam, a pearl is composed of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes (baroque pearls) occur. The…
A ruby is a pink to blood-red colored gemstone. The red color is caused mainly by the presence of chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires. Ruby is considered one of the four precious stones, together with sapphire, emerald and diamond. Prices of rubies are…
Peridot is one of the few gemstones that occur in only one color, an olive-green. The intensity and tint of the green, however, depends on how much iron is contained in the crystal structure, so the color of individual peridot gems can vary from yellow—to olive—to brownish-green. The most valued color is a dark olive-green.…
Sapphire (Greek; sappheiros, ‘blue stone’ is a typically blue gemstone variety of the mineral corundum. Trace amounts of elements such as iron, can give corundum a blue color. Chromium impurities in corundum yield pink or red tint, the latter being called ruby. Because of the remarkable hardness of sapphires – 9 on the Mohs scale…
Opal is a form of silica; its water content is usually between 6 and 10% Because of its amorphous character. Opal is the national gemstone of Australia. Australian opal has often been cited as accounting for 95-97% of the world’s supply of precious opal, with the state of South Australia accounting for 80% of the…
The name is derived from the colour – the yellow of the lemon – It won’t immediately take offence at being knocked about either, since its cleavage properties are non-existent. Amethysts and smoky quartzes can also be rendered yellow by so-called burning. This heat treatment at temperatures of between 470 and 560 degrees has to…
Tanzanite is the blue/violet variety of the mineral zoisite .It was discovered in the Mererani Hills of Manyara Region in Northern Tanzania in 1967, near the city of Arusha and Mount Kilimanjaro. Tanzanite is used as a gemstone. Naturally formed tanzanite is extremely rare[3] and is endemic only to the Mererani Hills.[4]Tanzanite is noted for…
Morganite is a light pink ‘family’ of the gemstone Beryl. It is named after the collector (and US banker) JP Morgan and can be found in a range of places including Brazil and Madagascar. You can get green Beryl (better known as emerald) too, but the most popular and well-known form of Beryl is the…