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Gemstone Crystal System Density Hardness Refractive index Treatments
cubic 3.51-3.53 10.0 2.417-2.420 heating, radiation, fracture filling




All colors.Diamonds most commonly occur in shades of yellow, gray and brown. The rarer stones are colorless and the rarest are reds, blues, pinks, greens in intense saturation.

Clarity: Transparent to opaque
Optic Character:
Cause of Color:
Yellow and Orange: Ni and related color centers
Green: Color centers due tonatural or artificial irradiation
Red, Pink, Brown: Unknown
Fluorescence: Inert to strong
Fracture : Step-like

Luster : Adamantine
Cleavage :
Four directions; perfect
Durability: Diamonds are the hardest of all gemstones. That refers to their ability to scratch. But they can be broken along their four planes of inherent cleavage.

Characteristics for Identification:
Naturals on the girdle, thermal inertial higher than simulants, bearding on girdle, adamantine luster

Diamond deposits are found world wide. The most noteable being Africa, Australia, India and most recently Canada.

Diamond is a polymorph (many forms) of the element carbon. Graphite is another polymorph. The two share the same chemistry, pure carbon, but have very different structures and properties. Diamond is hard, Graphite is soft (the "lead" of a pencil). Diamond is an excellent electrical insulator, Graphite is a good conductor of electricity. Diamond is the ultimate abrasive, Graphite is a very good lubricant. Diamond is transparent, Graphite is opaque. Diamond crystallizes in the Isometric system and graphite crystallizes in the hexagonal system. Somewhat of a surprise is that at surface temperatures and pressures, Graphite is the stable form of carbon. In fact, all diamonds at or near the surface of the Earth are currently undergoing a transformation into Graphite. This reaction, fortunately, is extremely slow.

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C (Carbon)
Diamond Grading: The 4 C's

Diamonds have long been valued for their hardness and incredible brilliance. Chemically a diamond is pure carbon, just like the graphite used in pencils. Diamonds' hardness is the result of extremely strong chemical bonds between the carbon atoms. Although most people think of diamonds as colorless, they actually occur in almost every color. Diamonds were viewed as talisman by the ancient Hindus in India, which is where diamonds were first discovered. The most powerful stones were thought to be naturally occurring octahedrons of exceptional clarity that exhibited fire. These stones would bring the owner power, wealth, everlasting youth and good fortune. It was believed that flawed or inclusive stones could have quite the opposite effect. During the first century AD prominent Romans wore uncut diamonds set in rings also as talismans. For hundreds of years it was believed that diamonds had gender. As late as 1566, Francois Ruet described two diamonds as having offspring. The first diamond engagement ring was given to Mary of Burgundy by Maximillian in 1477.

More Interseting Diamond Notes:

Clarity: diamond is transparent over a larger range of wavelengths (from the ultraviolet into the far infrared) than is any other substance
Thermal Conductivity: diamond conducts heat better than anything - five times better than the second best element, Silver!
Melting Point: diamond has the highest melting point (3820 degrees Kelvin)!

Lattice Density: The atoms of diamond are packed closer together than are the atoms of any other substance!

For information on the 4 C's, click here.