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Black coral inlay repair

#1

Greetings Orchidians, I have a challenge repair and I’m deciding how
to proceed.

Customer has a ring with a piece of black coral inlay in it. There
are two parallel grooves in the face of the coral that had gold
"bars" in it to give the illusion that there were 3 separate pieces
of black coral in the ring. The bars have fallen out. Apparently this
was a design problem, because it so happens this customer has two of
these rings and it happened to both (she thought she lost the first
ring, bought another and found the first)

She would like the missing bars replaced, I’m not sure about using
glue on such a tiny piece of gold (very thin square wire is what was
there) not to mention directly on the face of the coral. There does
not appear to be any kind of undercut on the gold surround the coral
that the “bars” join.

I was thinking of creating an undercut with a small graver, creating
a bar to size with angled ends to fit in the undercut, curving the
bar and trying to straighten it in place. Does this sound reasonable?

Thanks!
Barb Baur

#2

Black coral is not structurally sound enough to stand up to
hammering. I have inlayed many pieces and what i have done in the
past is to cut lines with a jewelers frame saw, then epoxy the bars
in to the coral. complete by filing the excess and it will serve to
fill;; the area so as to make it look as one. then leave a slight
amount hanging on the sides to force into the setting and then file,
then excess burnish and polish. Cutting with a graver will serve to
lift the fibrous structure of the coral. Ringman John

#3

Black coral can be drilled. Thus the wires can be posted and glued
in place. Solder two posts to each of your wires. Used the wires to
mark the placement of the wire in the grooves of the coral “stone” in
the setting. Using water to keep it cool, and drill two small holes
inside each line that are the same diameter as your posts. Use a good
epoxy and be sure to get some into the post holes. Finally, if you
are truely a fanatic, bend the posts that protrude through the
underside of the coral. They will never come out.

www.sumnersilverman.com

#4

Whoa there. I just had to respond to this one. Before you do any
drilling on black coral with water, you better know what kind you are
dealing with. Is it Antipatharian (deep water) or Gorgonian (shallow
water). It is not always easy to tell when the pieces are small and
finished. However, the Antipatharian will be slightly more brittle
than the Gorgonian which is relatively soft. Try giving it a knick
with a knife to see how it acts. If it is the former, water can be
used…if the latter, water will simply make the coral limp and it
will tear up as you drill it. Furthermore, if the latter, it will
swell with the water and contract as it dries and the size of the
hole will change dramatically. In fact if I where drilling either
coral, I would not use water. Rather, just use a medium speed and
push the drill slightly in and then retract it, push it in further
and retract it again, etc untill you are through (or as deep as you
wish to go). The reason for this, the coral is actually horney
protein material (both types are the same basic material) and if
heated even slightly by the drilling action, it will grab the drill
and break it in the hole. Retracting it gives it a chance to cool.
Also, if you do use posts as suggested, be sure to file some small
nicks around the metal part that will be glued inside the coral to
give the glue some bite. Cheers from Don at The Charles Belle Studio
in SOFL where simple elegance IS fine jewelry! @coralnut2