It's not an investment - at least not the pieces bought from De Beers. Blue diamonds or rarity sold/bought at Sotheby's is. Stuff sold at retail after feeding

It's not an investment - at least not the pieces bought from De Beers. Blue diamonds or rarity sold/bought at Sotheby's is. Stuff sold at retail after feeding long chain of middlemen at De Beers is not. Premium price is attached to the rarity occurring in nature + expensive post processing process, not to the intrinsic quality that is impossible to reproduce, because it is.