i was wondering if there would be any danger of crazing opals by
soaking them in acetone for a prolonged period of time... say two
or three days to remove them from an inlaid ring that has to be
sized up. And if there was any crazing or drying out, how could it
be remedied if at all
This is practically impossible to predict. As my favorite gemstone
to cut, polish, set, grade, appraise and just plain enjoy, it is
occasionally the most frustrating as well. Some opals will craze
seemingly at any moment for no reason at all, while others will
never craze. At least, not in my lifetime.
Opals, even stones from the same deposit may have differ widely in
porosity. Many polish up to a near-impervious finish while others
soak up liquids like a sponge. I don’t know of a test that can
differentiate one end from the other but I suspect that would have
the most bearing on whether your stone would craze.
However, if you must make this attempt, I would suggest Attack
solvent. I’ve had very good luck dissolving epoxies that hold pearls
or inlaid opal without affecting either in any measurable way. No
pearls have come back, nor have any crazed opals. Then again, if a
crazed opal comes back, I couldn’t say if it were caused by the
solvent, or whether it was just that particular opals’ “time to go.”
There is no remedy for a crazed opal other than recutting it along
the craze lines. However, a product called Opticon is often used to
"stabilize" crazed opal, as are UV curing glues. Bear in mind that a
crazed opal’s value is ruined and the use of products such as
Opticon, or one of the UV curing glues that are also occasionally
used does not remedy or restore the stone OR its’ value and is easily
detected by a decent gemologist. As an old friend of mine used to say
"Ya pays yer money and ya takes yer chances."
James S. Duncan, G.G.
James in SoFL