Diamonds, Sapphires, Rubies, and Emeralds

Why diamond Yes, it is hard, but it is its optical qualities (and great advertising) that have made it so popular. The refractive index of diamond is 2.42 while rutile (once proposed as a diamond simulant) and moissanite (now being used as such) have refractive indices of 2.6/2.9 and 2.65/2.69, respectively so it does not have the best optical properties (for internal reflection). 

Production began in 2003 in Lac de Gras 300 km northeast of Yellowknife it may be the richest diamond lode in the world. It has estimated reserves of 30 million tons and yields over 3ct per metric ton of ore (more than three times the world average). In 2005, 8 million ct were extracted valued at over US 400 million. 

Diamonds are actually mined in large quantities in South Africa and Russia with newer sources in Sierra Leone and northeast of Yellowknife in Canada s Northwest Territories. Natural diamonds are created 150km beneath the earth s surface and are transported to the 

For some time, nuxtures of H2 and natural gas have been used for chenucal vapor deposition (CVD) growth of diamond-like carbon (DLC) films. It is now possible to use this technique to grow diamond seed crystals to produce clear, perfect colorless diamonds. Diamonds grown by the high-pressure methods are invariably doped and thus colored. One company, Apollo, has used the CVD technique to grow 1-ct diamonds. 

The Centenary 273.85 ct Found in 1986 (de Beers Centenary) Rough weight 599ct In the Tower of London 

---

Gemstones. The most important gems are diamonds, sapphires, rubies, and emeralds. Gems must be harder than most other minerals, and they must be beautiful. Diamonds are composed of the element carbon, and rubies and sapphires are gem-quality varieties of the mineral corundum. Emeralds are gem-quality varieties of the mineral beryl. 

Gemstones must be attractive to viewers. Their attractiveness depends on the color, transparency, and luster of the gem and the way it is cut. The most important gemstones are diamonds, sapphires, rubies, and emeralds. Diamonds are often yellowish and transparent, with a hriUiant adamantine luster. Some of the most valuable diamonds, however, contain more intense green, red, blue, or black colors their rarity often makes them more valuable. 

Precious stone the most prized gem species usually limited to only four ruby, sapphire, diamond and emerald all others are semi-precious this is an artificial term used only in marketing and has nothing to do with quality, size, or value. 

A nickel-chrome spinel, NiO.CrjOg, has been made artificially in small green crystals. The green colour of emerald, serpentine, possibly sapphire, and other minerals is due to the presence of compounds of chromium, which also occur in rubies, corundums, and spinels. It has been shown that the peculiar spectra of ruby and diamond are due to chromium oxide which has been compelled to vibrate in an abnormal manner, leading to the production of narrow absorption bands. Traces of chromium have been detected in the soot produced by the combustion of coal obtained from deposits at Li ge. Compounds of chromium are not known to play any part in the economy of plants or animals. 

Gemstones Beryllium is also associated with gemstones. A gemstone is a mineral that can be cut and polished for use in jewelry. Some typical gemstones are jade, sapphire, diamond, ruby, amethyst, emerald, spinel, moonstone, topaz, aquamarine, opal, and turquoise. Gemstones are often used as birthstones, which honor the month in which a person is born. (For instance, the birthstone for April is a diamond.)... 

The best rubies and sapphires are so rare that the price per carat for individual specimens may exceed that for diamonds. Burma is the source for the best rubies and sapphires, and Colombia produces the finest emeralds. In 2006, total world emerald production was 5,400 kilograms, total ruby production was... 

Antiquity The shiny stones (especially diamond, sapphire, emerald and the ruby) are very researched, making it magical and curative properties attributed ... 

A conventional listing of the more important nonmetallics is presented in Table 12.2. Gemstones. A gemstone is a semi-precious or precious natural mineral with exceptional physical properties which, when cut and polished, can be used in jewelry. Only four minerals are considered as precious gemstones sensu stricto diamond, one gem variety of beryl (i.e., emerald green), and the two gem varieties of corundum (i.e., ruby, deep red, and sapphire deep blue). Beside natural minerals synthetic gemstones and their simulants are also found in jewelry. 

The cost of gemstones is driven by supply and demand. The most desirable gemstones—diamonds, rubies, emeralds, and sapphires—have the highest cost per carat. The price of a particular gemstone depends on the rarity of its color, its luster, the number of imperfections, and the desirability of its cut. The revenue from diamonds accounts for about 90 percent of that from aU gemstones. 

---