Hi Karen, I’ve never put any of this stuff through any gemological
tests, but a number of dealers who sell jewelry that contains it tell
me it’s glass.
According to them, some of it (emerald green colored obsidian) was
found near Mt St.Helen after the last eruption. The original find
was used up quickly & what’s being sold today is man made.
Based on a couple of dealers who’ve been selling the stuff at the
Tucson show since it hit the market I’d say it has staying power. I
don’t know if I’d call it a ‘fad’ or not, but because of the price
point it’s marketed in & the appealing color it seems to sell. Both
the dealers I talked to set it in 14K gold.