Bezel set opal and its double cab

Can’t understand why anyone would want to bezel set an opal, it seems
it would only create suspicion. A bezel setting will conceal a
doublet very well; thus, the popular advice to never buy an opal set
in that fashion. Prongs are the usual recommended method to set your
customer at ease for it will reveal the entire stone. If necessary
for design purpose, a half bezel will still allow the customer to
check the stone. Two reason why opals are fashioned as double
cabochon is that it is easier to polish a curved surface than a flat
one and also that the curved bottom makes the opal brighter and
livelier than a flat bottom piece. For those having problem with
making the seat to fit a curved bottom stone, try the lost wax method
and just apply the hot wax onto the bottom of the stone for a perfect
fit. To compensate for the shrinkage in casting, be sure to use
non-asbestos ribbon around the flask and use cristobolite investment.
Min Azama in Tokyo.

Dear Min, I have been bezel setting opals for 25 years in bezels
because they look better in bezels than in prongs. Also they are much
safer than in prongs where the edges can get banged up. Frankly,
almost all of the opals I have had to replace in repair jobs for
customers have been in prong settings. In the US, at least, I have
never heard of any advice, popular or otherwise, to only buy opals set
in prongs.

Daniel R. Spirer, G.G.
Spirer Somes Jewelers

JJA ponders: “Can’t understand why anyone would want to bezel set an
opal, it seems it would only create suspicion.”

In my opinion, it would only create suspicion when the seller of the
piece lets it happen by omission or commission. For me, opal doublets
are “real” where it counts and can be more than adequate when the
jewelery is more than a carrier of a valuable rock. I see no problem
when the artist uses a bezeled doublet as an element in the overall

Because triplets have an artificial top, I don’t consider them quite
"real". I’m sure many disagree.

In the end, it’s an “art thing”. If the work asks to be art and it
can’t survive without the dominating support of a high value rock,
then it’s probably not very successful art. Because rock transport and
presentation is a common goal of jewelery, it could be very successful


I’m just catching up on some back reading and could not pass up a
comment on this post. I have been cutting opals professionally for a
little over eight years now. I have never seen the need to cut a
"double cabochon" opal. While your comment about polishing a curved
surface is easier than polishing a flat surface it very true, that is
not the reason that opals are cut with a fat belly. Also, the
brightness from an opal is the result of light “REFLECTED” off the
color band, not transmitted light that passes through the stone, with
the exception of Contra Luis Opal. That is why the it is important to
cut the stone with the prime color band at the top surface of the
stone. A fat belly that would add to the depth of an opal does
nothing to enhance the brightness, in fact it may detract from it.
The main reason for a fat belly opal is to increase the weight. You
can add 20 to 30% in stone weight by cutting a fat belly. When you
are cutting a stone that will sell for $500 a ct, you can see the
profit motives for the fat belly.

One legitimate reason to cut a fat belly is to add to the structural
strength of the stone. For example, you have a stone that has a very
thin but very bright color band. Say it is a stone of larger than
average size, You could cut a large face but very thin stone and
take advantage of the color. It might not be very strong though. In
this case, to cut a moderate belly, just to give some additional
strength to the stone is appropriate.