All manmade, these gems are created when copper is introduced into molten glass. While beautiful, anyone who is buying these sold as "Natural" stones should be aware, they are not! (try running a google search on "what is goldstone made of?" to see for yourself). They can be an orange stone with golden sparkles throughout, or a black stone with blue sparkles. Again, they are very lovely stones, but I believe in informed buying...honest sellers have nothing to hide, right? :)