diamond types
https://www.goodreads.com/topic/show/20387698-10-sites-to-help-you-become-an-expert-in-blue-sapphire-rings-vintage
The heat that generates the diamond can even exceed 1,two hundred degrees Celsius. Anything at all under 400 degrees Celsius brings about graphite, not diamond. Look at warmth. It corresponds to the heat, the enthusiasm