What are Diamond Types?

Diamond Types
[Image Courtesy: Christies, Reena Ahluwalia]

You may have heard of terms Type Ia or Type IIa when referencing diamonds. What do they mean? Without getting overly technical, the nitrogen content found in mined and lab-grown diamonds allows us to categorize diamonds by “type.” This is based on the presence or absence of trace elements (aka impurities) in diamonds which are what give mined and lab-grown diamonds and gemstones their beautiful range of colors.


Currently, most near-colorless lab-grown diamonds are either Type IIa or are a combination of more than one diamond “type,” which is not found in mined diamonds. See below for the images depicting the Types. Type IIa contains little to no nitrogen, which is very rare in nature, but common in lab-grown diamonds. Chemically, it’s the most pure. Therefore, when identifying lab-grown diamonds, one of the first things to look for is the diamond type, since lab-grown diamonds classify as a diamond type that is extremely rare in nature.

IIa Diamonds
[Diamond Type – BDI Research]

Today, some of the most advanced non-laboratory testing available to separate mined and lab-grown diamonds use diamond type(s) as a basis for initial separation. Based on these findings, further testing at a gemological laboratory will be needed in order to conclude diagnostically whether it’s mined or lab-grown.


Think of diamond “types” as a form of gemological classification. There are two types, Type I and Type II. These two types are subdivided further into Type Ia, Type Ib, Type IIa, and Type IIb.


Type Ia:

  • Nitrogen atoms arranged in pair or clusters.

  • Around 98% of mined diamonds are Type Ia


Type Ib:

  • Nitrogen atoms are scattered or isolated instead


Type IIa:

  • Contain little to no nitrogen

  • Very rare in nature, while all lab-grown diamonds are Type IIa


Type IIb:

  • Contain boron, which colors them blue

  • Excellent conductor of electricity



What does this mean for you? There’s really no advantage or disadvantage to diamond types; 98% of mined diamonds are Type Ia, while all lab-grown diamonds are IIa.


Fun fact, a majority of the world’s most famous and large mined diamonds are Type IIa!

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