Hi Sharon,
Yes, Black diamonds are actual diamonds that have been treated by irradiation I believe.
The holes are very tiny and a pain to string, we use beadalon the thinnest available and we have not had any problems thus far from breakage, knock on wood.
Laurie
Natural black diamonds are not treated. Its the carbon that makes them black. If you are interested in black diamonds contact Amgad Inc.
http://www.ganoksin.com/resources/detail-amgad-2036.html
They deal in all natural color diamonds.