Diamond

Big Photo

Colourless (F) diamond
0.80 carats
© Fancydiamonds.net

A diamond (from the ancient Greek adámas, meaning "unbreakable," "proper," or "unalterable") is one of the best-known and most sought-after gemstones. Diamonds have been known to humankind and used as decorative items since ancient times; some of the earliest references can be traced to India.

The hardness of diamond and its high dispersion of light – giving the diamond its characteristic "fire" – make it useful for industrial applications and desirable as jewellery.

Perhaps the most famous use of the diamond in jewellery is in engagement rings, which became popular in the early to mid 20th century due to an advertising campaign by the De Beers company, though diamond rings have been used to symbolize engagements since at least the 15th century.

Diamond Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Diamond Gemstones by Size

This table shows distribution of Diamond gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.01 cts
Heaviest:189.62 cts
Average:2.85 cts
Total photos:317
Do you have a larger Diamond? Why not upload a photo?
Significant stones
Cullinan I (Star of Africa)530 cts
Orlov Diamond190 cts
0.01ct to 18.97ct18.97ct to 37.93ct37.93ct to 56.89ct56.89ct to 75.85ct75.85ct to 94.82ct94.82ct to 113.78ct113.78ct to 132.74ct132.74ct to 151.70ct151.70ct to 170.66ct170.66ct to 189.62ct
General Information
Varieties/Types:
Nano-Polycrystalline Diamond - An synthetic polycrystalline diamond.
Chemical Formula
C
Walter Schumann, Gemstones of the world (2001)
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Significant stones
ImageNameWeightCountry of OriginCurrent Owner
Cullinan I (Star of Africa)530.20 ctsSouth AfricaBritish Crown
Orlov Diamond190.00 ctsIndiaKremlin Diamond Fund
Darya-ye Noor Diamond182.00 ctsIndiaMuseum of Central Bank of Iran
Ahmed-Abad157.25 ctsIndia
Florentine137.27 ctsIndia
Tiffany (Yellow)128.54 ctsSouth AfricaTiffany & Co.
Portuguese127.01 cts
Koh-i-Noor105.60 ctsIndiaThe British Crown
Click here to view all significant Diamond gemstones
Diamond Treatments
The irradiation of a type Ia diamond,
followed by heating at 800°C, resulted in diamonds having a yellow or orange colour. This treatment is easily detected because an absorption line
is also produced between 594 and 595 nm; this absorption is very rarely seen in a faceted natural fancy-coloured diamond. With a type Ib diamond, either natural or synthetic HPHT, irradiation followed by annealing produces a treated pink diamond.
Radiation Followed by High Temperature (c.1400 °C) can give the diamond an attractive green colour.
A tinted yellow (cape) diamond could be given a fancy canary yellow colour by HPHT processing.Following this processing, it is possible to subject the diamond to irradiation and annealing at 800 °C. It gives the diamond a pink or mauve colour.
Diamond Simulants
An enormous number of materials, both natural and artificial, have been used as diamond simulants for thousands of years.

Glass, quartz and other gemstones have been used throughout recorded history to simulate Diamonds, but a true diamond simulant must have the high dispersion that is characteristic of diamond, and ideally be hard enough to be used as a gemstone.

lead glass - a glass with a high refractive index, has been used to simulate diamond for a very long time, it is of course much softer than diamond.

cubic zirconia, or CZ, is probably the most economically important diamond simulant, in use since the 1970s it is very similar visually to diamond but very low cost to produce.

Strontium titanate is an artificial gemstone that was used frequently as a diamond simulant from the mid 1950s until the 1970s.

Yttrium Aluminium Garnet or YAG, and Gadolinium Gallium Garnet or GGG, are two artificial garnet-type gemstones that were frequently used as diamond simulants in the early to mid 1970s, until the availability of cheap Cubic Zirconia.

Moissanite, or silicon carbide, is a much more recent synthetic gemstone, having been first produced commercially in 1998. Unlike most other diamond simulants, it has a very high hardness - second only to diamond itself in the gem world, with higher refractive index and dispersion than diamond.
Synthetic Diamond
Synthetic diamond: Colourless, yellow, brown, green, blue, red, pink; Transparent; Hardness 10; RI 2.417; Opt. isotropic; SG 3.52; Perfect cleavage; Fluorescence: SW - distinct yellow, yellowish-green or whitish-yellow; Inclusions: metallic residues (partly magnetic), internal growth and colour zoning - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 31
Physical Properties of Diamond
Mohs Hardness10
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Specific Gravity3.50 to 3.53
Walter Schumann, Gemstones of the world (2001)
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Cleavage QualityPerfect
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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FractureConchoidal,Splintery
Walter Schumann, Gemstones of the world (2001)
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Heat SensitivityHigh temperatures can induce etchings on the facets. Therefore special care must be taken during soldering!
Walter Schumann, Gemstones of the world (2001)
Refractive Index2.417 to 2.419
Walter Schumann, Gemstones of the world (2001)
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Optical CharacterIsotropic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) Anomalous double refractionMore from other references
PleochroismNone
Walter Schumann, Gemstones of the world (2001)
Dispersion
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