Diamond type system

With the advent of high tech spectroscopic equipment, more and more testing is done on diamonds. One recent branch of diamond study is the notion of “type” of diamond.

What is diamond type?

Diamond type refers to the make-up of the diamond crystal; pure diamond is 100% carbon atoms, arranged in a very regular, repeating pattern. However, most diamonds contain tiny amounts of other elements, most commonly nitrogen. Diamond type classifies the diamonds on the nature, amount and pattern of the other elements present.

What are the types of diamond?

There are two main types, type I and type II (pronounced “type one” and “type two”). Type I diamonds contain tiny amounts of nitrogen. The other two percent, type II, contain no nitrogen. A concentration as little as 0.1% of nitrogen present is enough to classify a diamond as type I.

Type I is further subdivided into type Ia and type Ib, depending on whether the nitrogen is present in individual atoms or as “clumps”. Type Ia account for 98% of the diamonds in the world.

Type II diamonds have no nitrogen. They were formed under high pressure for longer periods of time than type I diamonds. They are subdivided into type IIa and type IIb. Type IIa have no nitrogen or boron present, type IIb have a tiny amount of boron present.

Why is it important?

Diamond type has no bearing on the beauty of a diamond. However, studies have shown, for example, that yellow diamonds are type I, and that blue diamonds are type II. Knowing the type of the diamond being studied helps gem laboratories detect treated diamonds, as only some types of diamond can be enhanced.

How is it detected?

High tech laboratory equipment is necessary; fourier transform infra-red scpecroscopy, secondary ion mass spectrometry and electron spin resonance spectroscopy (among other tests) are performed.

Does it make any difference to the ring on my finger?

No! The sparkle and life in a diamond has no relation to diamond type.

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