I also have an opal to set. So any I will echo Jenny, any advice
will be appreciated.
I have been reading all that “sage” advice on setting opal, and I am
strongly advice to to ignore it.
There is a difference between been a goldsmith, or been a jewellery
hack. Goldsmith never uses adhesives of any kind. Gemstones are never
darken or lighten, or painted, or enhanced in any way. Gemstones are
never backed up with anything. If gemstone cut too thin to withstand
normal setting process, it should not set at all. If gemstone lacking
in natural appearance to stand on it’s own, it is not a gemstone, but
a rock and should not be used in jewellery.
With that in mind, we can talk about setting opals. First, precious
opal is alway cut with sufficient thickness. Thinly cut stones are
always a suspect of treatments, so only work with properly cut
Only select stones with water content less than 7 percent. How can
one know? If you work with a lot of opal, invest in hydrostatic
balance. As an alternative, most of school labs have them, your local
appraiser guy should, and etc. Opal density should be 2.15 or higher.
You also would need a polariscope. They are not expensive. Opals are
amorphous, but internal strain is commonly present, which manifest
itself as ADR ( anomalous double refraction ). Presence of ADR, by
itself, is not a deal breaker, but if pinfire opal displays strong
ADR, this is a warning sign. One looks for discrepancy between
pattern and presence of strain.
Assuming everything checks out, it is time to set our opal. Securing
stone in the setting must be the very last step. No polishing,
ultrasonic, steaming should even be contemplated. Choice between
bezel and prong is matter of preference. Opal can be successfully set
in prongs. Whatever method one choses, setting should be constructed
from 22 karat gold, or higher. Stone must fit into the setting so
that after mere placement, it can be lifted only with great
difficulty. That does not mean stone is pressed into setting,
absolutely not. Stone should settle under it’s own weight. After
stone is fitted, only slight displacement of metal is required to
secure the stone.