I'm sure many of you are familiar with the work of Steven
Kretchmer (http://www.jewelrystudio.com/designer/kreindex.htm). He
markets ring that hold a solitary stone with shank tension. Does
anyone know the proper procedure for tensioning a ring to securely
hold a stone? I am interested in learning this technique.
I’ve made four so far, basically teaching myself. Here’s a picture of
Basically, if casting, you must:
(a) choose a heat hardenable alloy
(c) squeeze it closed a bit
(d) heat harden it
(e) pry it open on a mandrel
(f) set the stone
(g) slide the ring off the mandrel
You can use a ring mandrel for tension setting some stones. The
sapphire ring in the picture above is actually done in sterling
silver. I have no clue if it’ll hold long term, but it’s an
experiment. To get that thing pried open, I pushed in a wooden wedge
with hand pressure until the two arms spread open enough to slip the
stone in. So far, it’s been in and worn for a couple of months, so so
far so good. I probably wouldn’t recommend using silver though.
My first ring I didn’t put very much pressure on the stone. It fell
out the next day. I reset the stone with more pressure and it’s held
for 8 months now.
My last ring I worked in white gold, and set the stone with too much
pressure. The ring, even though it was 4mm by 3mm (oval), cracked
under its own pressure. Nickel white gold can exert quite a bit of
pressure it seems :-). The diamond was OK.
I’m entirely self taught, and don’t have any means for measuring
what’s appropriate. I think though, that when I do this again, I will
make the ring to size, squeeze it 2mm smaller than the stone it is
going to hold, heat harden, then pry it open and set the stone. The
nickel white gold ring was closed to 3mm, and it was just too much. I
had a feeling because I’m a big guy (I once bench pressed 315 pounds,
though I’m not nearly that strong these days :-), and I could not get
the ring off the mandrel without a hammer. Previously, I’ve been able
to use my thumbs to push the ring off with the stone in place.
All of the rings I’ve done have notches where the stone fits in.
For setting tips, push the ring up the mandrel until you can snugly
fit the stone in… then you just gently, ever so gently, slide the
ring off. Again, in my last case I had to whack it with a hammer, and
I don’t think that’s a very recommended approach… required some
timing and luck to get it that way :-).
In the last case, even though the ring cracked, and the cracked arm
bent up under its own pressure, and the stone was now at a 30 degree
angle, it still stayed in, and I could not pry the ring open with my
fingers (couldn’t really get them into the ring though, so I couldn’t
apply much strength). Tension rings are pretty solid things if done
I absolutely love the look of the things, and they’re my favorite
thing to make!