A type IIb diamond contains boron, which can make it blue or gray. The boron also lets it conduct electricity.
In more detail
That is why a blue diamond can read "moissanite" on an electrical tester. Labs grow boron-blue diamonds too, so a blue stone that conducts needs a gem lab.
Related terms
- Electrical conductivity tester: An electrical conductivity tester checks whether a stone conducts electricity. Many moissanites conduct, and most near-colorless diamonds do not.
- Fancy color diamond: A fancy color diamond is a colored diamond with enough color for a fancy grade. To GIA, any diamond outside the D-to-Z scale is a colored diamond.
- Laboratory-grown diamond: A laboratory-grown diamond is a diamond that people grow with machines, by HPHT or CVD. It has essentially the same composition, crystal structure and properties as a natural diamond.