The name "Diamond" (Diamante French or German, Diamante Spanish or Italian) is derived from the name from the Greek adamas, "unconquerable", referring to its hardness. At one time over 80% of the world's rough diamonds passed through the Diamond Trading Company or DTC, which is a subsidiary of De Beers in London. In the late 1990s, Canadian prospectors discovered several abundant sources of diamonds. The Canadian Ekati Diamond Mine was opened in 1998 and produces 3 million carats of rough diamonds every year. The Diavik Diamond Mine was opened in 2004. Diamonds are mined in alluvial mining operations when they are not located along a kimberlite pipe.

Diamonds are categorized and valued according to the "Four C's" of diamond grading. They are cut, clarity, color, and carat. For more information on this grading system, go to: Diamond Grading - The Four "Cs". The largest diamond ever found was the Cullinan Diamond in 1905.

Diamond has a hardness of 10 on the Mohs scale. The Toughness of Diamond is Good. Diamonds crystallize in the isometric or cubic crystal system, with a "octehedral" crystal habit. Diamond is typically associated with igneous rock kimberlites.

Diamond is a natural allotrope of carbon. The main allotrope of carbon is graphite. The crystal bond structure of diamonds give the stone its hardness and differentiates it from graphite (Diamond Chemistry). Diamond is the hardest natural occurring material. Diamonds are one of the most prized gemstones; however, diamonds have industrial applications as well. Diamond is a transparent, optically isotropic crystal with a specific gravity of 3.52, a refractive index of 2.417, and a high dispersion of 0.044.

Diamonds crystallize in the cubic crystal system and consist of tetrahedrally bonded carbon atoms. The brilliance and luster of diamonds are described as adamantine, which means diamond-like. Some diamonds exhibit fluorescence of various colors (usually blue) under long wave ultra-violet light, but generally bluish-white, yellowish or greenish fluorescence under X-rays. Canadian diamonds, however, show no fluorescence. Diamond is singly refractive (isotropic) with a refractive index of 2.417.

Chemical composition: C
Diamond History
Due to their incredible hardness, diamonds were probably used a cutting or drilling tools, prior to their use in ornamentation. There known use dates back as far as the 4th century BC. Pliny the Elder (23-79 AD) wrote about 'adamas' (diamonds) in his encyclopedia "Historia naturalis," stating: "The substance that possesses the greatest value, not only among precious stones, but of all human possessions, is adamas; a mineral which for a long time, was known to kings only, and to very few of them," adding that diamonds are: "tested upon the anvil, and will resist the blow to such an extent as to make the iron rebound and the very anvil split asunder."

Source: Afghanistan, Brazil, Canada (Regal Ridge), Columbia, Madagascar, Pakistan, Zambia.
Birthstone: May
The name "Emerald" (Émeraude French, Smaragd German, Esmeralda Spanish) comes from the Greek word smaragdos, a name that was given to several gemstone minerals having little in common chemically, but sharing a similar bluish-green color. An emerald is a form of Beryl, a mineral group that includes aquamarine and Morganite. Emerald's leaf-green color is partially due to allochromatic coloration from trace amounts of chromium (Cr) and vanadium (V) impurities.

Emerald is a composition of Beryl (a cyclosilicate of beryllium and aluminium), and along with chromium and vanadium, other emerald coloring agents include Beryllium (Berillium) (Be) Aluminum Silicate and Iron (Fe). Many varieties of emerald have a leaf-green to yellowish-green hue, but Columbian emeralds have a particularly intense greenish hue with a bluish-green overtones, which makes their color very difficult to capture in photographic images.
Although emeralds have a hardness of 7.5 to 8 on the Mohs scale, the toughness of emerald is only fair to poor due to the high amounts of inclusions and fractures in the stone. Emerald crystalizes in the hexagonal crystal system, with a "hexagonal prism" crystal habit and pincoid terminations. Emerald has a Vitreous luster and a refractive index of 1.576. Emerald is typically associated with igneous rock.

Chemical composition: Al2Be3[Si6O18]
Emerald is one of the most difficult gemstones to cut because of the many fluid inclusions found in rough crystals which can make them very brittle. These multiphase inclusions are like fingerprints and can reveal the geographic location of their origin. The French refer to the large number of inclusions in the stone as "jardin," or "garden," because they can resemble plant foliage.

Emeralds with many inclusions should be treated with care and be protected from direct blows to the stone. Oils are commonly used to fill-in the fissures (see "emerald enhancements" below). The extreme rarity of transparent, inclusion-free emeralds can make them more valuable than diamonds.

The name "Ruby" (Rubis French, Rubin German, Rubino Spanish or Italian) is Latin for red. The fiery red color of ruby was thought to be an inextinguishable flame lit from within. Rubies were celebrated in the Bible and in ancient Sanskrit writings as the most precious of all gemstones. Ruby is also known as the "stone of Kings". Some of the finest rubies in the world are mined in Myanmar and Thailand. Other significant sources for rubies include Kenya, Afghanistan (Jagdalek, Jagdalak, or Jagdalik), Madagascar, Pakistan, Sri Lanka, Tanzania, and Vietnam.

The ruby belongs to the same "aluminium oxide" mineral family (corundum) as sapphire and is formed by heat and pressure in limestone rich in clay. The primary origin of ruby is metamorphic rocks and volcanic igneous rock or basalt, and secondarily alluvial. Ruby is made up of the mineral corundum, which is aluminum oxide or alumina. It becomes a ruby when it has a small impurity of chromic (III) oxide (chromium) which gives it the rich red coloration. If the corundum has other impurities such as iron and titanium which will give it a blue color, it is called sapphire. Rubies can be transparent to totally opaque, and have a vitreous to dull greasy luster.

Ruby and sapphire gems also sometimes exhibit a six-pointed "star" or "asteriated" effect from reflection off microscopic, needle-shaped rutile crystals (also referred to in the ruby trade as "silk") which intersect at 60° angles. Star rubies are semi-transparent to opaque, and the star effect is more apparent when a cabochon cut is used for the stone.

Ruby has a hardness of 9 on the Mohs scale. Corundum has no cleavage planes, but does have a conchoidal fracture, and can be parted more easily in certain directions. The Toughness of Ruby is Excellent. Ruby is categorized in the hexagonal crystal system with a tabular crystal habit. Ruby has a refractive index of 1.760. Rubies are commonly subjected to artificial enhancements such as heat-treating, fracture-filling, flux-healing to improve color and repair fractures and inclusions.

Chemical composition: BeAl2O3

The name "Sapphire" (Saphir French or German, Zafir Spanish, Zaffiro Italian) is originally derived from Greek (sappheiros), the Sanskrit word sanipruja ("dear to Saturn"), and the Hebrew word sappir, meaning gem. The biblical Sapphira was a woman who was executed by God for lying. The oldest Sapphire mines are situated in Ceylon, or Sri Lanka.

Sapphire belongs to the same "aluminium oxide" mineral family (corundum) as Ruby, but sapphire is more abundant than ruby due to the larger occurrence of its coloring agents. Sapphires (Corundum) have a hardness of 9 on the Mohs scale.

Corundum has no cleavage planes, but does have a conchoidal fracture, and can be parted more easily in certain directions. The Toughness of Sapphire is Excellent. Sapphire is categorized in the trigonal crystal system with a crystal habit of forming into a six-sided barrel-shape tapering into a pyramid (below). Sapphire has a refractive index of 1.760.

Chemical composition: BeAl2O3
The blue coloration of sapphire is due to charge transfer involving Iron (Fe) and Titanium (Ti). There is also a pink variety of sapphire which is heat-treated. The primary origin of sapphire is alluvial. Both Sapphires and rubies exhibit double refraction, which resolves a beam of incident light into two beams which emerge with different colors. These two gems also sometimes exhibit a six-pointed "star" or "asteriated" effect from reflection off microscopic, needle-shaped rutile crystals which intersect at 60° angles. When these stones are cut in a cabochon shape, they display this star-shaped light pattern giving them the name "Star Sapphire