as an Aussie, I’ve set a fair bit of precious opal over
the years. Cutting an accurate bearing for the opal is of paramount
importance. If the opal is pressed down on a high spot in the bearing, it
will often crack at that point. One of the tricks is to smear a very very
thin trace of araldite around the bearing. The plasticity acts as a “shock
absorber” when you are pushing over the bezel or claw. I do the same with
emeralds, but remember, only a tiny smear - otherwise it can show up
through the stone.
The choice of setting metal is not always ours to make, but if you can, go
for the softest alloy available. When I have the option, I choose to use a
fine, 0.5mm thin, platinum bezel on the more precious pieces of opal.
Platinum sets opal like a dream and I’ve never had any problems.
Hope this helps. Regards, Rex from Oz.