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Diamonds Index
Coloured Diamonds are Very Rare
Fancy Coloured Diamonds are Very Rare

Uncut Diamonds of Many Colours
Uncut Diamonds of Many Colours

Diamond Types
Diamonds can be scientifically classified into 4 types, known as type 1a, 1b, 2a, and 2b.
Diamonds are made of carbon, and are extremely pure, but in almost all diamonds there are tiny proportions of other elements, interspersed within the carbon as part of their crystal structure. These "impurities" are not what are known as inclusions, and are so small as to be invisible even under a very powerful microscope.

Type 1 Diamonds
Type 1 diamonds contain nitrogen. About 98% of all diamonds are type 1a

Type 1a
If the nitrogen atoms are clustered together within the carbon lattice, then the diamond is said to be a Type 1a diamond. Because these diamonds absorb blue light, they can have a pale yellow or brown color. 98% of diamonds are Type 1a.

Type 1b
If the nitrogen atoms are evenly spread out throughout the carbon lattice, then the diamond is said to be a Type 1b diamond. These diamonds absorb green light as well as blue light, and have a darker color than type 1a diamonds. Depending on the precise concentration and spread of the nitrogen atoms, these diamonds can appear deep yellow ("canary"), orange, brown or greenish. Less then 0.1% of diamonds belong to Type 1b.

Type 2
Type 2 are diamonds that absorbed no, or very few, nitrogen atoms.

Type 2a
These diamonds can be considered as the "purest of the pure" - they contain no, or minuscule amounts of impurities and are usually colorless. Unless, that is, the carbon tetrahedrons that make up the diamond were twisted and bent out of shape while the diamond rose to the surface of the earth. An imperfect carbon lattice will make the diamond absorb some light, which will give it a yellow, brown or even pink or red color. 1-2% of diamonds belong to Type 2a.

Type 2b
These diamonds contain no nitrogen - but they do contain boron, which absorbs red, orange and yellow light. These diamonds therefore usually appear to be blue, although they can also be grey or nearly colorless. All naturally blue diamonds belong to Type 2b, which makes up 0.1% of all diamonds.

Summary of Diamond Classification
TypePrevalenceFeatureColours
1a98%Clustered Nitrogen AtomsColourless, Yellow
1b0.1%Scattered Nitrogen AtomsYellow, Orange, Brown
2a1 - 2%Highly Pure CarbonColourless, Yellow, Brown, Pink, Purple
2b0.1%Boron AtomsBlue, Gray

Green Diamonds
Green diamonds are a separate case: these diamonds can contain clustered nitrogen atoms or they can contain no nitrogen atoms - what gives them their color is that they have been bombarded by nuclear rays during their growth. This bombardment makes them absorb magenta wavelengths, which gives them their green color. These diamonds are extremely rare.

Type 1 or I, Type 2 or II
Some works cite the diamond types as Ia, Ib, IIa, and IIb, rather than 1a, 1b, 2a, and 2b. As you can see, we have chosen to use Arabic numerals rather than Latin.

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