History & Introduction

The name 'diamond' comes from the Greek word, 'adamas', which means 'invincible.' Diamond consist of different qualities and is unique mineral. It is the hardest substance in the world and is famous for the greatest conductor of heat, consist of the highest melting point of any substance (7362° F or 4090° C), and it has the highest refractive index than any natural mineral. Diamonds have the greatest number of wavelengths. Below or at room temperature diamonds are tend to feel cold due to heat conduction. When heat is provided to the diamond it will remain hot long even after the heat source is removed.

The superlative physical qualities of diamond are credited to the strong covalent tetrahedral bonding between its transparent crystals. Diamond's cubic crystal pattern is also completely symmetrical that refracts light in all directions at the same velocity.

According the hardness and refractive index slightly vary among Diamond specimens. In case of Bort and Carbonado slightly lower hardness is shown, and lack cleavage. Lonsdaleite or Hexagonal Diamond is a kind of Diamond with meteorites and is of extra-terrestrial origin. Scientifically it is different mineral than Diamond, and it is created when meteoric Graphite fell to earth. With this action great heat and stress transformed the Graphite into Diamond, however it took Graphite's hexagonal crystal lattice.

Diamonds are not only prized and famed for their exceptional hardness, however also due to their high refractive index (brilliance) and presenting of remarkably high dispersion rate of visible light (fire). Even though traditional colorless or 'white diamonds' are the most popular color diamonds, yet yellow and brown diamonds (champagne and cognac) are actually the most commonly occurring diamonds. Red diamonds are considered to be the rarest gemstones in the world.

Availability - A major portion of the world's diamonds is extracted from Central and Southern Africa. The levels of production of diamonds vary year by year. In 2010, the leading diamond producers were Russia, Congo, Angola, South Africa, Botswana, Namibia, Ghana, Guinea, Australia and Canada. There have also been major deposits found in India and Brazil. Canada, currently main commercial source for fine white diamonds.

Buying Guide

Color - Mainly we find diamonds colorless or 'white', still the most common colors are yellow and brown. Golden and brownish hues are because of the presence of traces of nitrogen impurities. Yellow along with brown and yellow diamonds are often referred to as 'champagne' or 'cognac' diamonds. Besides these even colors like pink, red, orange, blue, green, grey and black are included. Blue diamond get the color because of impurities from boron, while other fancy colors occur due to irradiation and also due to crystal lattice defects in some cases. The official color grading system for colorless to low-saturation yellow and brown diamonds ranges in scale from 'D' (completely colorless) to 'Z' (light-yellow). Grading of fancy colors are on an entirely different scale.

Clarity and Lustre - Diamonds shows a strong sub-metallic adamantine luster. In fact diamonds are from transparent to opaque, where the transparent stones are faceted. The diamonds are mainly too heavily flawed to be considered valuable. Nearly, 20% of all diamond deposits are of any gemstone value. About 20% yield the vast majority will still contain flaws and inclusions even if they are minute. In fact the diamond that is flawless is very rare.

Clarity of diamond is graded on a scale including size and visibility of flaws and inclusions. Even if the diamond clarity grading scale is taken official, an assigned clarity grade for any single specimen can vary tremendously depending on who did the evaluation or where the stone was evaluated. It is common for a single stone to be given two different clarity grades by two different labs - the same goes for cut and color grading of white diamonds.

Cut and Shape - Nowadays in diamonds the brilliant cut is the most prevalent cut that is followed by the 'passion cut' - both of which attempt to maximize a diamond's brilliance and fire through precision faceting and proportioning. Cuts that are modified like brilliant cuts, step cuts and mixed cuts (rose cuts) are not as common as they once were in the past. The most popular diamond shape is round. To add on to the shapes it includes pear, oval, radiant, princess (square), emerald (octagon), asscher, cushion, heart and trillion (triangular) shapes.

Treatment - Champagne, cognac and colorless 'white' diamonds are treated naturally. But it may be enhanced artificially. Drilling through Laser is used to remove inclusions; fissures and cracks may be artificially filled with glass. There are various fancy colors that are present naturally, however most are produced through irradiation or high pressure / temperature treatment. Diamonds are frequently imitated or simulated. The procedure to synthesize diamonds is very difficult and expensive, however lab-grown synthetic diamonds can be found.

Usages- Diamonds are favourite in the jewellery market. Due to its qualities like hardness, brilliance and rarity of Diamond, makes the stone famous. Transparent diamonds mostly are used jewellery purpose, although recently yellow and brown gems have gained popularity. Colored Diamonds like red, pink, blue, green, and purple, are called as Fancies, and are rare and also have exorbitant prices.

For gem only 20 percent of Diamonds are fit to use. The other 80 percent mined are used in industries, particularly as abrasives and as Diamond saws that are rotary saws with tiny Diamond studs that can cut in fact anything. The only way to cut and polish a Diamond gem is with a Diamond saw. The diamonds are also used as thermal insulators, in electronics as well as in optics.

Gemological Characteristics:

Chemical Formula	C
Crystal Structure	Cubic (or isometric)
Colors	Colorless, yellow, brown; rarely green, blue, red, orange, grey, black
Hardness	10 on the Mohs scale
Refractive Index	2.417 to 2.419
Density	3.50 to 3.53
Cleavage	Perfect
Transparency	Transparent to opaque
Double Refraction or Birefringence	None
Lustre	The lustre of Diamond is excellent. Rough Diamonds exhibit a greasy lustre, but proper cutting give them a powerful adamantine lustre.
Fluorescence	Variable
Chemical Composition	Carbon
Fracture	Conchoidal
Tenacity	Brittle
Striking Features	Immense hardness, adamantine luster, and specific localities
Environment	Formed in plutonic rocks in the form of cylindrical plugs known as pipes, and usually formed deep underground. Also occurs in alluvial placer deposits.
Rock Type	Igneous, sedimentary
Popularity (1-4)	1
Prevalence (1-3)	3
Demand (1-3)	1

Classification:

• Colorless
• White
• Yellow
• Brown
• Black
• Gray
• Green
• Red
• Orange
• Pink
• purple