Type I

Ia

Ib

Prevalence

98%

0.1%

Color centers

Clustered Nitrogen atoms

Isolated Nitrogen atoms

color

Colorless
Yellow

Orange
Orange Yellow
Brown

Type II

IIa

IIb

Prevalence

1-2%

0.1%

Color centers

No specific color center

Boron atoms

color

Colorless
Yellow Brown
Pink
Purple

Blue
Gray