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Tension set in sterling


#1

I need help! Is it possible to tension set a stone in sterling? If
so, how? If you pass on the secret I will be your very best friend.

Thank you all,
Richard Langbert


#2
Is it possible to tension set a stone in sterling? If so, how? If
you pass on the secret I will be your very best friend. 

Me too. Me too!! Would love to know how to tension set.

Michele


#3
Is it possible to tension set a stone in sterling? If so, how? If
you pass on the secret I will be your very best friend. 

There are not secrets in goldsmithing. And that is the biggest
secret of them all. Extraordinary things are accomplished with
ordinary means.

I have no idea how to tension set a stone. Even if I did, I would
strongly advice against it. I can show how to set a stone, that would
appear to be tension set ( whatever that means )

First, why not tension set?

I do not believe it is a good idea to leave any gemstone, especially
diamond, under constant stress. Gemstones have cleavage. Application
of moderate force over time, could have the same effect as sharp
blow.

So how do we do it? Realize that any setting is a type of a
"tension". What we call a prong, en engineer would call a cantilever
beam. Six prong setting, in engineers mind, would be a structure
made of six cantilever beams. ( cantilever beam is a beam which is
supported on one end only )

“Tension setting” is a two prong or cantilever beams, construction.
The base of structure is the point opposite the gemstone, on the ring
shank. In another words, the whole ring becomes a 2 prong setting,
with the center of the shank been the structural base.

The cross-section of the base is important. If it is rectangular,
with longest dimension parallel to the width of the shank, the base
would be weak. A trapezoid, providing it is taller than wider, would
be quite strong.

You must prepare the ring, with exact dimension, like stone is
already set, but without the actual stone. All sizing and shaping
must be done. Open the ring just enough to insert the stone. At this
point stone is quite loose. But should be able to stay in the opening
by itself. All we need to do is to tighten the prongs, so to speak.
There are two ways to do it.

By twisting the ends in the direction perpendicular to the shank
axis, going back and forth, you can create tension to close the gap.
That is similar to tightening the prong moving it sideways. I do not
like this method, because it is difficult to do with heavy shanks,
and it does have residual tension on the stone.

The second method is heat. Put ring in heavy soldering tweezes.
Pressure should be in the direction of the closure. Slowly heat with
the torch the area of the shank directly opposite the stone. You do
not need to take it to the read heat. Once you see colors on the
metal, you should observe that shank would close on the gemstone,
under pressure from tweezes. Of course, do not take this process too
far. Do not handle, until ring is cooled of on its own.

Leonid Surpin
www.studioarete.com


#4
Is it possible to tension set a stone in sterling? If so, how? If
you pass on the secret I will be your very best friend. 

I would not even think of trying. Put a circle under the girdle and
use a heavy shank or plan on loosing lots of stones. Sterling is just
not stiff or hard enough. Know your materials not your wishes.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#5

Cold forge the ring so that the metal is displaced more than 50% to
get it work-hardened. The finished metal needs to be thick so as to
be solid and tough. Cut the grooves deep for the girdle bits
because…

…tell the customer that neither you nor any other jeweller will be
able to guarantee nor re-size the ring.

A better option may be an under-support that is virtually invisible,
that ties the ring into a complete unit, exposes more of the stone,
and can be re-sized and guaranteed.

Alastair


#6

Sure you can make a tension set ring out of silver. However the stone
will not stay tight. Tension set rings are copyrighted by the company
that makes them and is made out of a proprietary metal that has the
right amount of tension in it. Though they look cool, they are very
uncomfortable to wear because the shank has to be very thick and the
same thickness all around thus making the space between the fingers
very wide.

If you still want to make one out of silver, simply make a heavy pipe
style band that is open at the top. Cut the seat for the stone. Then
slide the ring on a mandrel up a size or two to open the top. Slide
your stone into place and then bring the ring back down the mandrel
to the desired size and to tighten the stone. I’d recommend using a
diamond or precision cut synthetics. Softer stone may just crumble.

Have fun and make lots of jewelry.
Jo Haemer
www.timothywgreen.com


#7

Well, Michelle and all, it’s really quite simple - you get a well
cut if not ideal cut stone, then you cut a “perfect” seat for it on
either side - no room for error, here. Then you cinch the bottom of
the shank so it pushes the top together, with the stone in place.
That’s how I’ve done it, anyway.

But you’d have to be nuts to do it, and doubly so in silver. You may
notice there’s not a huge number of people doing it, because it’s a
"showcase ring". They look good in the cases and magazine shots, but
they have no legs. One pop and that stone is gone, and you, the
maker, are liable for it…

That one guy (who’s name escapes me) who is famous for it, and has
patents, is using special alloys and they have engineered it to the
tiniest detail.

In any case, you could follow the steps I said above, in sterling,
but you’ll get nothing but trouble for it - or you’ll need a shank
so big it will dwarf the stone. If you want to try, it’s not that
hard, mechanically. It’s just that the successful ones are
intimately tied to certain alloys with strength and spring and the
like… It’s not just method, it’s also metal.


#8

I suppose you can make an “illusion” tension set ring by placing a
seat for the stone to stay secured with. I have the idea in my head
and I’d love to try it but I’m not up to that level of
experimentation yet. :slight_smile:

Michele


#9

Although I wont make a tension set ring or recommend that anyone
ever buy one i have a possibility for you.

The concept of a tension set ring is, strong immoveable precious
metal and a gemstone tough enough to take the pressure.

Regular sterling does not do so well as a spring, however…

If you are determined to try this which i hope you are because a
failure of this type is at least positive in the " well, you learned
something category" i have a theory or a possibility of how to make
this work if you can do your own casting AND if you can alloy your
own sterling, try replacing a few % of the copper, say 4% by weight
to the alloy with silicone bronze (3.75 % copper & 4%S.B.).

you can or, at least used to be able to get it at the welding supply
in the form of silicone bronze brazing rods. My experimental results
ended up with an alloy that made cuff bracelets which were really
springy and difficult to mangle -

goo


#10

I’d strongly suggest that you tell your customer that tension
setting a stone in silver is not a wise decision. Silver can’t be
hardened enough to retain sufficient tension to ensure the stone will
stay in place.

Part of your reputation is built on giving good advice as well as
quality work & design.

Tension set rings are made from a patented metal that retains it
shape under daily wearing.

Dave


#11
Sterling is just not stiff or hard enough. Know your materials not
your wishes. 

This is completely correct. Why not altering the alloy? I have made
some Shibiushi lately and I still surprises me how hard this alloy
becomes and how fast it hardens. It needs to be annealed after three
or four passes through a rolling mill (I used appr. 30 % copper). Of
course, you cannnot stamp it as Sterling, but you could put a patina
on it and have a black ring. It’s worth a try and much less
complicated than adding Germanium and/or Cobalt to the main metal
and make try outs.

Leach


#12
Sterling is just not stiff or hard enough. Know your materials not
your wishes. 

What about Platinum Sterling?

Elaine
http://www.CreativeTextureTools.com


#13

My daughter recently got engaged and of course wanted her dad to make
the engagement ring. I sourced a nice VVS/G round diamond of a size
that suited their budget,the stone is 0.30ct. My daughter expressed
an interest in having a white gold tension set ring design. As the
diamond was very nice I persueded my daughter to let me make a ring
that resembled a tension set but wasn’t. I followed the tension set
design but added a collet beneath the stone to strengthen the
circumference of the ring. looking down on the stone it looks like it
may be tension set, but I feel safer knowing my daughter will
hopefully not lose the stone easily.

The attachment shows the finished ring, simple but nice.

Peace and good health to all.
James Miller FIPG


#14

While I didn’t get this right from the mad scientist himself, I did
get it second hand thru my one time boss from the (late) Mr.
Kretchmer. The ring is made of a special heat treatable alloy. After
stone is set, its heat treated to basically an unyielding status.

No you can’t do it at home, no you can’t do it in a typical shop.
You certainly can’t do it with any alloy that isn’t specific to the
task.

If it could be done in sterling you’d no doubt see lots of
illegitimate knockoffs but you don’t.


#15

For examples of tension set rings, www.stevenkretchmer.com or
www.niessingshop.com. Opposing sides where the groove is cut for the
girdle are parallel across the face from side to side, face is flat
(Neissing) or sloping gaining thickness toward bottom(Kretchmer)
from what I see.

Kretchmer alsohas a bypass ring that is tension set.

Richard Hart G.G.
Denver, Co.


#16
What about Platinum Sterling? 

Not particular to Elaine’s quote, but it needs to made very, very
clear, I think. I’ve done it before - you make a ring, you cut two
bearing cuts very precisely, insert the stone and squeeze the ring
together, which holds the stone in place. You can do it in copper,
fine silver, 24kt gold. What you can’t do is wear it, and you
certainly can’t guarantee a $20k diamond that way. What is
~required~ to do that is to use metal that has strength approaching
steel. It’s a fine example of art and engineering - the facade of it
is simple and easy - make it in sterling, snap a photo, and scrap it.
Making a REAL piece of jewelry that can be worn - most importantly
guaranteed - requires much engineering. Even with the engneering, I
don’t trust them an inch. You MUST guarantee that the customer will
have a stone in a year, or two or three - you’ll be sued anyway if
you don’t, so you may as well own up to it from the beginning. Make a
ring, set the stone, and then put two fingers inside the circle and
try to pull it open as hard as you can.

If the stone comes the tiniest bit loose, your ring is junk. Even if
it doesn’t there’s always that risk…


#17
What is ~required~ to do that is to use metal that has strength
approaching steel. 

It’s a bit more than just strength. As John says, the trick is making
a tension set ring that not only looks good, but which can hold the
stone securely over time. To work properly, it’s no so much the
strength of the metal, but it’s elasticity. The ring must function as
a fairly strong compression spring. That means that if you pry it
apart a bit, it will spring back when released, all the way to it’s
initial postion, with no deformation resulting from being pried
apart. Then, if the strength of the metal is such that the force
required to thus pry it apart is high enough so it won’t happen,
well, then and only then, might the stone be secure. The above is a
bit of a tall order. Many strong metals will reach an elastic limit
when deformed only a fairly small distance. You need one which simply
won’t get bent permanently out of shape with any deforming action. If
you then have the stone seated sufficiently deeply and accuratly into
the facing surfaces, the amount of deformation then needed to rully
release the stone would require more force than the ring would be
expected to experience, and anything less, though the stone would be
loose while the ring was sprung apart, it would be again fully tight
when allowed to return to it’s normal state. A ring like this, such
as those designed by the late Steven Kretchmer, or Niessing in
Germany, will be a very secure setting. Better than normal prong
settings where prong can be bent away from a stone with much less
effort. Less secure, perhaps than a fully set bezel, which would have
to actually wear away to release the stone. But adequate security,
even for a costly stone, is possible with the right design and metals
choices.

As John says, this is as much engineering and metalurgy as it is
jewelry design.

While you could use fully work hardened sterling silver of a heavy
guage to make what would look like a tension set ring, sterling
simply doesn’t normally have enough strength and elasticity. Given a
good “bend”, it won’t fully recover. So a good tension set ring would
be difficult to do, and a poor idea for anything costly.

I have a memory of a description by my “then” boss, who’d visited
the Kretchmer workshops, of how they set their stones in the tension
set rings. He described the seats being cut to extreme precision in
the finished rings, to the exact dimensions of the stone. Then, the
ring held in a heavy machinists vise, large size heavy vice grip
pliers were used, sometimes with two people, to pry the rings ends
apart enough to slip in the stones. When released, the ends snapped
back into position, and the stone was tight and secure. From this
description, (which may not, after these some years, be precisly
accurate, but close enough) you can get the idea of just what level
of strength and spring is required to do these things right. The
majority or the copies you might see made by other firms with lesser
engineering simply won’t function properly and stones won’t be
secure. Mr. Kretchmer engineered his own alloys to give these
properties, and the designs of the rings supplemented the alloy’s
properties. You can’t for example, make the shoulders of tne ring
nice and heavy, but then taper and thin the back of the shank.
Comfortable, yes, but no longer strong enough. The entire ring, all
the way around, has to function as that uniform compression spring,
The back of the shank has to be as strong, or stronger, as the front
shoulders.

All in all, tension set rings should not be considered a "normal"
design choice. For one, there are techical patents and design
copyrights that cover many of the features of workable tension set
rings. And for another, many jewelers simply don’t have the technical
expertise to do these effectively. I’m not at all sure I could pull
one off well, at least not on the first two or three tries. And I’m
no beginner. I’m also not willing to risk having to replace those
first two or three lost stones…

Cheers
Peter Rowe


#18

Here’s a question I’ve often wondered about, Peter.

My understanding is that Steve Kretchemer developed a (patented)
heat treatable alloy for the tensinion (compression) rings.

What about Niessing?
Andy


#19
Here's a question I've often wondered about, Peter. My
understanding is that Steve Kretchemer developed a (patented) heat
treatable alloy for the tensinion (compression) rings. What about
Niessing? 

So far as I know, the alloy Steven developed was primarily the heat
treatable platinum alloy. He may have also tweaked the various gold
alloys he used. The the big developement alloy wise, was the platinum
one.

Niessing, so far as I know, never used platinum for tension sets. I
could be wrong on that, but I’m pretty sure of it. Standard white,
yellow, and rose gold alloys can be mixed up to be capable of age
hardening sufficently to provide a good tension setting, and I’m
pretty sure this is what they did.

For my money, at least structurally, Kretchmers’ rings were/(are?)
stronger. Niessing relied a bit more on the sheer weight of the
mountings to provide the strength, in addition to using hardenable
alloys. Kretchmer refined the hardening methods and alloys more,
which gave him considerably greater design leeway.

Peter


#20
What about Niessing? 

From what is published, one can learn that they cold forge their
rings, and resizing is a matter of exchanging the ring against the
right size.

If you speak about protecting the design, Niessing holds
well-defended design rights. When rights expire, they still hunt the
violator as can be read here: http://tinyurl.com/niessing

It could be argued that design protection is stronger than patents.
If you have deep pockets, that is. I have never seen any tension
ring other than Niessing while I lived in Germany. But Niessing is
available everywhere. I bet they regret that they haven’t
trademarked the design worldwide.