Most natural diamonds are classified as which type?

• A. Type Ib
• B. Type IIa
• C. Type Ia
• D. Type IIb

Answer: (C)

Diamonds are classified by how nitrogen is present in their crystal lattice and how those nitrogen atoms are arranged. In most natural diamonds, nitrogen isn’t isolated but occurs in paired forms and in larger clusters. This arrangement defines them as Type Ia. This type is by far the most common among natural diamonds, and the nitrogen aggregation state influences color tendencies and how the stone behaves in spectroscopy.

Other types are rarer: Type Ib has nitrogen atoms dispersed individually and can contribute to more noticeable coloration, Type IIa contains little to no nitrogen and is prized for extreme colorlessness, and Type IIb contains boron and often has a blue tint. So the reason Type Ia is the best answer is that its nitrogen is predominantly in aggregated forms, making it the most typical for natural diamonds.