There is no possibility that they are man made opal if you mean
synthetic opal - having the same properties as real opal. They are
man-made glass imitation opals. Quite distinct and easy to recognize.
I went through all my books and can't find it. I know at saw them in one
of the books. All I can figure is I mis-placed one of the books. Sorry I
didn't find it for you.
It all depends on the appearance of the stone, the way they are set and
what they are set in. I can't find my silver book that has some of
these, but if I find it, I'll see if I can find some pricing
information. Generally less than book value on eBa...
They are art glass and are a common version of glass opals. Usually they
are described as fire opals or black opals, but they are glass. I happen
to adore these vintage glass cabs.
