Also known as a diamond type 2a diamond, a Type IIa is one of four diamond classifications. Around 1-2% of all diamonds are classified as Type IIa (or 2a).
These gems are purely, or almost purely carbon, and are considered to be the purest and most valuable of all.
Type IIa diamonds have zero or exceptionally few nitrogen atoms within the crystal lattice structure. These diamonds can be completely colorless. However, some have a brown, light gray, pink, or yellow hue.
Type I diamonds consist of carbon and nitrogen atoms. If the atoms of nitrogen are in crystal 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 have a blue or grayish-blue color. They are also known as the great conductors of electricity, unlike other diamond types.
Other Diamond Types: Type IIB, IA, and IB
TYPE IIB DIAMOND
Type 2b diamonds are nitrogen-free but contain boron. Boron tends to soak up the yellow, orange, and red light, which can result in the diamond emitting a very faint blue or grey hue.
TYPE IA DIAMOND
Most diamonds (around 98%) are classified as type 1a diamonds. This classification indicates that nitrogen atoms are clustered together inside the carbon lattice. Type 1a diamonds sometimes look colorless, but they tend to soak up blue light and can emit a very pale-yellow hue.
TYPE IB DIAMOND
Around only 0.1% of all diamonds are classified as type 1b. This classification is given if the nitrogen atoms are scattered around the carbon lattice rather than bunched together. Type 1b diamonds soak up blue and green light and look darker than type 1a diamonds – colors include brown, orange, and yellow hues.