Honestly, you don't even need to specify 'brown', regular diamonds would apply. DeBeers has some awesome marketing, diamonds are one of the least beautiful gemstones.

Beauty depends entirely on the cut. (If you haven't seen diamonds with "old european" cuts - late 19th century, essentially - you should. They are so much more beautiful than the sterile modern cut ones)

s/brown/"chocolate"/

black pearls too no?