The 1%.

That is what IIa diamonds are, part of the 1%. More accurately, the less than 1-2%, of gem quality-diamonds that are mined throughout the globe. This is reflected in the price, as they command a premium if and when they are for sale. 

Every retail jeweller or your own research when Google-ing will teach you about the 4 Cs (cut, colour, clarity and carat). Yet less focus is put on the types of diamonds. There are types: Ia, Ib, IIa and IIb. Each type is used to identify and classify diamonds. Based on colour classification and the amount (or lack) of impurities (nitrogen atoms) present. No doubt you remember the Winston Pink Legacy a IIa pink diamond, recently sold at Christie’s in Geneva.

Lesedi IIa diamond

Internationally, there are a handful of reputable gem labs. They provide certification (via examination and reports) as well as contribute valuable data to the scientific community.