Can you cut them? If you know how to make cabs, I have the address
of the person that bought the Gilson process somewhere, and you can
buy the rough and cut it pretty cheaply.
There are many types of synthetic opals that claim to be "Gilson
like", but they are very different. I embed opal in hot glass, and
Gilson is the only one that dosent turn to ash immediately.
At the last intergem show, I was given a sample of some
'not-plastic' opal, took it home, put it in glass, came back the
nest day to the show and gave it to the dealer. It was a tiny black
dot of carbon in the glass. He was surprised, it was sold to him as
The last time I bought a bunch of Gilson, it was about $15 a ct in
the rough for the good stuff. It, like other stones and rough, comes
in various grades. I also have selections of Opals for sale, if you
are interested in real opal.