The list of precious metals that may be used for granulation does not end
with gold and silver. I am familiar with someone who, after much
experimentation, has mastered the technique of platinum granulation.
Although I do not know the specifics, he keeps those under tight wraps ;
}, I have seen several pieces that were absolutely amazing.
Granulation techniques are not limited to 22kt gold, although this tends
to be easier for a lot of people than fine silver, sterling silver or
18kt gold, which are also great to use for granulation.
Intrica Fine Jewelry