Nano-Polycrystalline Diamond - An synthetic polycrystalline diamond.
|Photos of natural/un-cut material from mindat.org|
|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.
|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: 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 Hardness||10Blue Chart Gem Identification (2010) , More from other references|
|Specific Gravity||3.50 to 3.53Gemstones of the world (2001) , More from other references|
|Cleavage Quality||PerfectGemmological Tables (2004) , More from other references|
|Fracture||Conchoidal,SplinteryGemstones of the world (2001) , More from other references|
|Heat Sensitivity||High temperatures can induce etchings on the facets. Therefore special care must be taken during soldering!Gemstones of the world (2001) ,|
|Optical Properties of Diamond|
|Refractive Index||2.417 to 2.419Gemstones of the world (2001) , More from other references|
|Optical Character||IsotropicBlue Chart Gem Identification (2010) , Anomalous double refractionMore from other references|
|Pleochroism||NoneGemstones of the world (2001) ,|
|Dispersion||0.044Gems, Sixth Edition (2006) , More from other references|
|Colour (General)||Colorless, yellow, brown, rarely green, blue, reddish, orange blackGemstones of the world (2001) , More from other references|
|Transparency||Transparent,Translucent,OpaqueGemmological Tables (2004) , More from other references|
|Lustre||Adamantine,GreasyGems, Sixth Edition (2006) , Adamantine to greasyMore from other references|
|Fluorescence & other light emissions|
|Fluorescence (General)||Very variable: Colorless and yellow: mostly blue; Brownish and greenish: often greenGemstones of the world (2001) , More from other references|
|Fluorescence (Short Wave UV)||Weaker reaction if any. Yellow: rare weak yellow to orange. Blue: rare yellowish to bluishBlue Chart Gem Identification (2010) , More from other references|
|Fluorescence (Long-Wave UV)||Usually blue (and yellow phosphorescence). Colorless (near-colorless): tylically strong blue. Yellow: inert to strong blue, yellow (also green, rarely orange). Pink (and red): mostly blue (yellowish to orangy phosphorescence). Blue: rare orangy. Green, brown: greenBlue Chart Gem Identification (2010) , More from other references|
|Fluorescence (X-RAY)||Most diamonds show a rather uniform bluish white glow; the exceptions are those diamonds which show a yellow glow under|
UV and show a similar glow under X-rays but this is not always so.Gems, Sixth Edition (2006) ,
|Crystallography of Diamond|
|Crystal System||IsometricBlue Chart Gem Identification (2010) , More from other references|
|Habit||Mainly octahedrons, also cubes, rhombic dodecahedrons, twins, plates.Gemstones of the world (2001) , More from other references|
|Where found:||It is known to be the product of the deep-seated crystallization of ultrabasic igneous magmas which have intruded as dikes or pipes of kimberlite or lamproiteGems, Sixth Edition (2006) ,|
|Inclusions in Diamond|
|Inclusions: olivine, garnet, diopside, graphite, tension and cleavage cracks, growth zoning, twinning lamellaes - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 31|
|Mineral information:||Diamond information at mindat.org|
|Significant Gem Localities|