According to the chemical build of the stone, they are classified as Type Ia, Type Ib, Type IIa, or Type IIb stone. Interestingly, one stone can actually be classified as more than one specific type of diamond, as is the case in most stones in the market today.
Type I diamonds are the most common. They represent 98% of all natural diamonds and have detectable traces of Nitrogen.
Type Ia diamonds contain clusters of Nitrogen atoms throughout the crystal structure of the stone. They tend to emit a yellowish tone.
Type Ib diamonds contain Nitrogen atoms as well. These atoms are all singular as opposed to clustered groups. These stones are 0.1% of all diamonds and emit a strong yellow, orange, brown and even green color tone.
Type IIa diamonds are the most valuable and consequently are very collectable items. They contain either very little or no Nitrogen atoms in the crystal structure of the stones. White stones are exceptionally colorless and fancy colored diamonds are often found with a brown, purple, or pink tone. They represent only 1% - 2% of all diamonds.
Type IIb diamonds contain elements of Boron within the structure. As a result, they often emit a blue or gray tone. They represent only 0.1% of diamonds. And consequently, they are also very valuable.
In short, Type IIa and Type IIb stones are the most unique and the “purest of pure”.