Natural-color green diamonds are very rare. Of all diamonds cut into polished gems in any given year, a very small number of them will have a dominant green color. Diamonds with a natural green color are rare enough that many people have never seen one, and those who have seen one are likely to have seen it in a museum exhibit.
You are unlikely to find a natural-color green diamond in a mall jewelry store. But even though green diamonds are extremely rare, there are a few companies who have a long history in the retail colored diamonds business. So, anyone who wants a natural-color green diamond and can afford one should be able to find a selection of gems to consider. (geology.com)