Black diamonds are thought to have originated from a star and are also called carbonados.
Their structure is comprised of millions of small crystals clustered together. Unlike the structure of conventional diamonds they are therefore much more difficult to cut.
Among the world's largest and most famous gemstones they include the Black Diamond of Bahia (350 carats), the Table of Islam (160.18 carats) and the Black Star of Africa (202 carats).
Generally most black diamonds, especially those which are not certificated are heated to give them their vibrant black color. Heating black diamonds is often considered as an acceptable industry practice for them—given their look and price point. Black diamonds are the only treated (or heated) diamonds that Prijems carries.