Gold tellurides come in different names like calaverite, sylvanite
There are also scores of mineral compounds for the PGEs (six
platinum group elements) so gold and platinum are not as unreactive
as usually thought. Platinum even bonds with iron. But these gold
and platinum compounds are more than compounds: They are crystals.
I see crystals in nature which I don’t think a jeweller can surpass.
As crystallography advances and even diamond and ruby crystals are
grown in labs, jewellers may wish to learn more about the rarer
crystals of precious metals.