Diamonds by presence of the natural impurities are divided into two main types:
Type I and Type II that are also divided into subtypes.
|Type I||Type II|
Type I diamonds consist of carbon and nitrogen atoms. If the atoms of nitrogen are in crystalic pairs and they do not affect the diamond's color; this type is called Type IaA.
If the nitrogen atoms are in larger quantities and impart a yellow to brown tint to a diamond, it’s Type IaB.
If the nitrogen atoms are not paired or grouped throughout the crystal in isolated sites, they give the stone an intense yellow or even brownish tint, this is Type Ib.
Lab-grown diamond containing nitrogen is called Type Ib.
Type II diamonds don’t have or show any presence of nitrogen atoms in the crystal structure. They’re divided into Type IIa and Type IIb.
Type IIa diamonds are the most valued and the purest type of diamonds. They contain either very little or no nitrogen atoms and that leads them to colorless grade. They represent only 1% - 2% of all mined diamonds in the world. Most of the lab-grown diamonds are Type IIa. They can also be found in gray, light yellow, light pink or light brown hues due to structural anomalies arising through deformation during crystal growth.
Type IIb contains the boron atoms in the crystal structure, which makes most of the diamonds having a blue or grayish-blue color. They are also known as the great conductors of electricity unlike other diamond types.