Back to Ganoksin | FAQ | Contact

Sizing "Tension set"


#1

Any experiences out there on sizing up tension set rings? Gaby-Canada


#2

Yes, Don’t do it. This type of setting needs to re-hardened after it
has been sized. It’s my understanding that the stone is under about
10,000PSI of pressure and requires special equipment to harden the
ring. I have ALWAYS sent these rings back to the manufacturer for
sizing, as well as ‘Cabana’ and ‘Bagley and Hotchkiss’ Opal inlay
rings.

T.J.
a.k.a. Dean Amick
Hamilton Jewelers
Princeton NJ


#3

Gaby, I have had a lot of experience with tension settings.There are
many variables to consider.The shape of the stone?How large or small
you have to make the ring?Are there accent stones?What do you mean by
tension set?I have seen stones set in a variety of “tension sets” that
really should not have been set that way.Remember when you cut the
ring if you are enlarging it when you spread the shank open on your
mandrel.You can be putting more pressure on the edges of the stone
where they are seated.This can cause any stone to break.Color or
Diamond.When going down you can be moving the seats far apart so as to
loosen the stone.Depending on the ring if Iam going up more than say a
size and a half I will use two pairs of pliers (half rounded) to bend
the shank about at the half way mark again depending on the ring so
the shape is oval this keeps the pressure on the stone from
changing.Then I solder the shank and very very gently will tap it
round with a leather mallet on my mandrel.Can you send a picture of
the ring out?This would help.Hope this helps.J Morley Coyote Ridge
Studio Where the apples are fallin faster than we can pick them up.


#4
    Any experiences out there on sizing up tension set rings?
Gaby-Canada 

A true “tension setting” is in fact a spring. Any break in that
spring will result in a weak spot. Remember the proverb about the
weakest link? Same thing applies here. If the ring is cut and welded,
that area will have a different temper from the rest of the ring. It
will also probably end up either sligthtly thinner or slightly
thicker. If it is thinner, all tension in the ring will work on the
thin spot. If it is slightly thicker, all tension will work against
each side of the thick spot. The deal is that a once homogenous piece
of metal will now have hard and soft areas. Pretty hard to restore to
it’s previous springyness.


#5
   Remember when you cut the ring if you are enlarging it when you
spread the shank open on your mandrel.You can be putting more
pressure on the edges of the stone where they are seated. 

J Morley, if I’m not mistaken, a true tension set ring would fall in
half when sawed through on the bottom. There is no bridge holding
the top of the ring together to hold the stone - only the tension of
the alloys working against the host metal to put pressure on the stone
and thus hold it into place. This is achieved by annealing the metal
to set the stone and then strengthening it through a heating process.
This task is generally best suited to the company who manufactured the
piece. As a general rule, most companies use variations on the
alloys, all of which may respond a bit differently to the
heat-tensioning process. You might well be thinking of a channel
style mounting, which is supported underneath with the stone being
held into place by metal pressure from the top. Sorry if I
misunderstood your post. Mike


#6

Mike, No, Mike your probably not mistaken.She did not state in her
post that it was a “true” tension setting.Iam totally aware of
"true"tension settings.There was a very long(yawn) thread discussing
Steven Kretchners ownership of the "true"tension setting or alloy
mixture or whatever a while back…I truly did not mean to mislead
her.I have seen many untrue tension settings that are sold as tension
settings and have sized many of these and simply relayed such.At my
age (47) I try not to split too many hairs with people.I have
plenty,but most don’t and need all the hair they can get.Yours
"truly"J Morley Coyote Ridge Studio Where the apples are fallin and
the Coyotes are laughin


#7

To all,

I’ve been reading this thread with some puzzlement, and after reading
the latest, I had to jump in. A true tension set ring is open at the
top, holding the stone in by pressure from both sides of the ring.
You can’t cut the ring to size it, as you would end up with two ring
halves and a loose diamond. The company we have dealt with in the
past told me that you have only a couple of options regarding sizing,
and it can only go a small amount either direction. Larger requires
grinding some metal out of the inside of the ring, and smaller must
have sizing bars (balls) soldered to the inside of the shank. Any
larger size adjustments require re-making the ring.

I think there must be some misunderstanding in Orchidland as to
exactly what a tension set ring is, or maybe this aging bench jockey
is not up on the latest designs.

JMF


#8

Gaby ,that is one experience one should avoid. If it is a quality
piece ,such as a well know designer piece I would suggest that it
goes back to the maker .Or at least the place in which it was
purchased. It does not have to be your problem.


#9
   Yes, Don't do it. This type of setting needs to re-hardened
after it has been sized. It's my understanding that the stone is
under about 10,000PSI of pressure and requires special equipment to
harden the ring. I have ALWAYS sent these rings back to the
manufacturer for sizing, as well as 'Cabana' and 'Bagley and
Hotchkiss' Opal inlay rings. 

I’ll second that, especially with tension sets from Steve Kretchmer,
who of course is the only U.S. manufacturer who’s got the patents and
copyrights (not to mention the metalurgical expertise) to make them
properly. One correction though. With well done tension sets, there
is only a little actual pressure on the stone. Just enough to hold it
firmly in position. What you’re referring to is the types of forces
(and I don’t recall the exact numbers) that are resisting the removal
of the stone. Unlike a prong, which can be bent back by only a little
bit of pressure against a hard point or surface or tool, the tension
sets are held over a much wider area of the girdle, and the entire
setting must be sprung away from the stone to actually remove it.
Since the whole point of such settings is that the metal is highly
conditioned to a spring condition, slight deflections that might, in
unusual situations, spring the setting apart a bit, don’t hurt since
the setting instantly springs right back to it’s original position due
to it’s being engineered as a compression spring. It does not need to
actually exert much force on the gem. It only needs to maintain it’s
own shape, or if sprung apart, return to that shape. Then the stone
can only be lost if the ring is sprung so far apart as to allow the
stone to escape all in the one event. THAT takes a lot of force.
When they’re made, after heat treating, it can take heavy duty vices
and vice grip pliers and similar tools that really don’t look
appropriate around fine jewelry to spring the setting apart far enough
to insert the stone in the already cut seat. Once release, the
setting then springs in again, and the stone is secure unless someone
exerts similar forces on the ring again, or some jeweler is foolish
enough to try and size the darn thing.

As a general rule, when selling tension sets, be sure you’ve got the
size right the first time, and make sure the customer is aware that
sizing these things is NOT routine or practical. Some of Steves
designs pretty much require remaking the ring in order to size it…
And he understandably does not just give that service away for free.
Properly sizing those that CAN be sized still requires the use of
fairly high tech equipment, and then some very careful and precise
heat treatments to restore the hardness and spring of the setting.
Leave this to the folks who made the ring, and fully understand the
alloy they’ve used.

And if by chance, you’ve got a U.S. made tension set ring that is NOT
a Steve Kretchmer piece, then do yourself a favor and still don’t go
near the thing. Most likely, it’s a knock off of the design, but made
in an alloy that does not have sufficient hardness and spring to allow
it to properly function. Should you attempt to size it, then WHEN the
stone loosens (which it eventually would have done anyway) then YOU’LL
be caught in the crossfire. Even if it’s properly made, it like as
not violates Steves patents and copyrights. If it’s from Germany, on
the other hand, then maybe it’s ethically OK. But still, size it at
your own peril. If you can determine the alloy, and it’s required
heat treating cycles, then, if you can properly fuse/weld the sizing
job (usually needs a laser or heliarc, at least for the platinum ones)
so as to create a seamless job (don’t use solder, and don’t thin it
out. It needs the thickness) you’ll still need to have removed the
stone first, sized it, heat treated it again, and then will have to
wrestle the stone back into the mounting.

have fun.

Peter Rowe


#10

I recently bought second hand a Steve Kretchmer ring, with a .81 SI1
D as the center stone. (The ring had his stamp and a 1990 copyright
inside.) I had some reserve about how I 'd get the stone out of the
mtg, that it took special high tech tools: "THAT takes a lot of
force. When they’re made, after heat treating, it can take heavy
duty vices and vice grip pliers and similar tools that really don’t
look appropriate around fine jewelry to spring the setting apart far
enough to insert the stone in the already cut seat. " Sense we do
our own design and I bought the ring for the stone, I put the ring
on my mandrel tapped a little bit and the stone was out in less
than 20 seconds. There is in no way that I’d recommend this type of
setting to a customer of mine. I think its a big myth that the stone
is secularly set. If a customer were to take the ring in for
cleaning to a crook, the stone could be replace in less than a
minute.

Thomas Jones RJ