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Bezel thickness for opals


#1

Hi I’m planing to make bezels to be mounted with opals for a set of
earrings,ring and pendant. My question is which would be the most
appropriate thickness of the bezel in order to burnish the bezel over
the opal without damage it considering the fragility of the opals.
would it be a good idea if I just use glue? Any advice would be
appreciated Jonathan


#2

We usually use 28 ga bezels on opals. We also would use either 22k
gold or fine silver in order to minimize the chance of damage to the
stones.

Daniel R. Spirer, G.G.
@spirersomes
www.spirersomes.com


#3

Dear Jonathon I have bezel set opals in 22K and fine silver ( both at
30 gauge ) with no problems…Rio makes a 30 gauge fine silver saw
tooth bezel that works very well, as you can bend the points over
with an orange stick, that completely removes the chance of
scratching the stone

HTH
Ron


#4
 Which would be the most appropriate thickness of the bezel in
order to burnish the bezel over the opal without damage. 

I use 30 gauge bezel wire (fine silver or 22k) for all the stones I
set, including opals � and I set a lot (!) of them (both solid and
boulder). Opals are much sturdier than their relative softness would
suggest. Just use normal care but try to avoid a lot of downward
pressure, especially with opals that, because of uneven or rounded
backs, aren’t fully supported. Of the many hundreds of opals I’ve
set, I’ve cracked maybe 3 or 4 from carelessness or pushing too hard.

If you check the Orchid Gallery, you’ll find a piece I made from
eleven Mintabie precious opals. I cracked the first stone I set from
pushing too hard and had to replace it. These stones had a slightly
rounded bottom that made them vulnerable and I wasn’t paying
attention. After that I used a hand hammering technique when I needed
it (a very small punch made from a broken drill bur shaft) and had no
more problems.

As for glue, if you feel you need it for a little extra stability, I
see nothing wrong with that, but you should still use normal bezel
setting techniques to set the stones and not depend on the glue to
hold them.

Beth


#5

Jonathan, I like to use 18K in a 24ga thickness. I dress the bezel
to a knife edge that has a long taper. Something like a 30 deg angle.
If the mounting has a closed back, I will put a very thin layer of
sawdust under the stone as added protection. If you are setting
crystal opal in a closed back, you will have to resort to using a
black backing. For this, I usually mix up a batch of epoxy colored
with either lamp black or nigrosene. Confine it to the back of the
opal though as even a fine layer will show along the bezel.

Make sure that all of the bumps are removed inside the bezel. Also,
make sure the opal has a slight radius on the bottom of the girdle.
This will be of great help in preventing cracking. If you need to
dress the stone, use a 400 grit wet-or-dry wet to shape the edge and
follow with a through sanding with 1200. Keep the diamond files away
from the opal. They are to aggressive and will cause subsurface
damage which will translate to a cracked stone later. Watch the
sandpaper on the face of the stone as it will put a scratch area on
it in the blink of an eye.

Finally keep the tools away from the opal. I use a bezel rocker with
a well polished edge to push the bezel down, then use a burnisher to
smooth it out. I finish off the bezel with a pink silicon wheel. It
is soft enough so as not to damage the opal. Just watch the heat
build up though, it will crack a stone.

Don


#6

You can also use a barrel drill bit and gently remove some of the
inside of a bezel to thin it out and make it easier to push over the
stone. I always “thin-out” 14K gold this way.

Cheers
Virginia Lyons


#7

I think that the truest answer here is simply to use the bezel wall
thickness that you can comfortably set according to your skill level,
and also for the look that you want to achieve. Some people like to
use thin (30ga) bezel walls using a soft metal like fine silver or
22k gold. Personally, I find that these often wear out too quickly,
especially on rings, so I like to use a heavier, harder alloy like
18k with a lot of copper and a wall thickness of .3mm to 1.25mm.
Sure, it is harder to set, but I have been doing this for many, many
years.

I also agree with those who use a base of epoxy inside the bezel. I
don’t use the epoxy as the sole means of securing the stone, but as a
softer base to absorb shocks and to level the underside of the stone.
Let the epoxy semi-harden, then “bed” the stone. After the epoxy has
set, close your bezel around the stone. This technique requires you
to be very exacting on the fit of your bezel, or the end result will
look sloppy. With transparent or semitransparent stones, I tint the
epoxy, usually flat black.

Doug Zaruba


#8
With transparent or semitransparent stones, I tint the >epoxy,
usually flat black. 

Doug, I work in silver and have always blackened the inside of the
bezel with Liver of Sulfer before setting a crystal opal. I like your
idea better… What are you tinting the epoxy with?

Shane Morris


#9

Beth, I do not understand why opals are cut with a rounded back in
the first place. Is it simply to give them more weight to charge more
for them? Would it be advisable to flatten the backs if one has
finished stones that shape? Thank you,

Rose Alene McArthur
@O_B_McArthurs


#10

Dear Marcos Mondragon/Jonathan

I’ve set quite a few opals and here is my 2 cents worth about it: If
you are going to set it in silver I would recommend 999 silver/pure
silver as it is softer than sterling. A thickness of 0,3 to 0,5 mm
would be appropriate. As for gold, I normally use 18 kt or 22 kt,
also because of the relative softness.

All opals are quite brittle, some types more than others, but I
always make sure that I have a very firm and tight fitting seat for
the stone so that it will not move during setting. Moving during
setting is what causes almost all chippings of opals, believe you me,
i’ve tried it ;-). You can achieve that tight fitting seat by either
cutting the seat very accurately or by making a tight fit seat of
glue.

I know that this might start (again) a long discussion about the
ethics of setting with glue, but actually you need not glue the opal
in, but using an epoxy glue is a very easy way to get a good fit.

And may I wish you a happy setting.

Kind regards
Betty & Niels L�vschal, Jyllinge, Denmark
@L_F8vschal
phone (+45) 46 78 89 94


#11

I also use 18k & 22k for bezel when setting opals. The other thing I
will do before I set an opal, especially if it is a boulder opal, is
to sand the bottom of the opal. This creates a flat surface and helps
a great deal with the opal rocking in the bezel.

Michael
Metalwerks@aol.com


#12

If you do not glue the stone in what do you do with the epoxie. I
think that it would be hard to shape. Marilyn Smith

I know that this might start (again) a long discussion about the ethics
of setting with glue, but actually you need not glue the opal in, but
using an epoxy glue is a very easy way to get a good fit.


#13

Dear Rose, I don’t know for sure why opals (and many transparent
gemstone cabs) are cut with rounded backs. I do know that it’s
traditional and I’d guess the reason has to do with protection and/or
open backed settings. If the reason is to protect the edges of the
stones, however, they’d be better off with flat backs and beveled
edges, the way most opaque cabs are cut. And, since I set most cabs
with closed bezels, the rounded backs are a hindrance not a help.

So, what to do about it? If the stone is opaque (boulder opal, mabe
pearl) by all means flatten the back (or create an epoxy or other seat
for it as has been suggested on this thread). If the stone is
transparent, however, you’ve got another problem since, if you flatten
the back you then need to repolish it or the transparency and beauty
of the stone will be diminished. Unless you’re a lapidary and/or don’t
mind spending the time, you’re better off setting it (carefully) as is
or creating a seat for it.

Beth


#14

I make my bezels about 1mm thick or more. Silver or gold, 10K. 14K,
18K or 24K makes no difference. I make the bezel about 1/2 the
thickness if the bezel too small. I then cut a seat for the stone.
This supports the stone at the girdle. After the bezel is soldered
into place, and I have reached a good time to set, I will plane down
the top of the bezel until it is approximately 1/2 mm above the stone
at the girdle. I will then taper the bezel to about 45 degrees leaving
about 1/4 mm thickness atn the top. At this point the stone is set
into the bezel and I will use a chasing hammer and bronze punch to
hammer the bezel top straight down. Due to the taper, the bezel is
inflenced to collapse onto the stone. Before it is down completely, I
will usually burnish the inside of the bezel with a bronze needle
shaped burnisher and then finish hammering.

The measurements above may be larger or smaller, depending on the
design and job.

All of this makes discussion of a a rounded stone belly somewhat
academic. The girdle of stones should be rounded. This eliminates
razor sharp edges that easily chip and when those chips are conchoidal
in nature can really mess up what may have been an otherwise nice day
as recutting or polishing can remove a considerable amount of material.


#15

Rose, I have cut countless opals…most with flat/beveled backs but
now and then with rounded low dome backs. Why? One is to provide
added strength if the stone tends to be thin. Sometimes the dome will
be pootch with no color but the added depth of the stone often will
increase the intensity of the color across the crown. Not much sense
making the girdle area thick as that is normally hid by the bezel or
bearing anyway. In such a case, the cutter may actually reduce the
weight in favor of maintaining a strong play of color in the center.

Another is to follow the vein, especially if it widens out and then
shoals off at the edges. This way, more of the precious opal is saved
even though it may not be seen when set. If one wants to consider this
as cutting for weight, so be it, but I consider it more as the
preservation of beauty. I mean, why cut away precious color just to
achieve a flat back?

Another is to make the back of a stone with strong color finished so
it can be set in an opan back setting and the beauty can be seen as it
moves about.

Finally, many opals are set in open back ring settings etc, and the
native cutters were taught to leave a dome so that the edge would fit
the bearing of the setting while the dome would dip down into the open
area and ‘stabilize’ the stone. With more modern designs this is not
necessarily the style and the dome provides little stability.

With massssss production of settings, I used to do a regular business
of repairing or replacing cracked stones that were set in poorly
constructed settings. If properly made, a setting will support the
stone evenly all around and it should last many years given normal
wear. If the setting is not exact, then there is nothing wrong with
using the g word (glue) to ensure a stable supportive bearing. Just
don’t over do the amount used!

If I had a stone with a domed back, I would not flatten it other
than perhaps to correct poor cutting. Rather, build a setting that
accommodates it and retain all that beauty.

Cheers, Don at The Charles Belle Studio in SOFL where simple elegance
IS fine jewelry!


#16

Marcos: You can use the thinnest metal that you can solder using the
more soft metal like Silver 98%or gold 22k. The only problem is to
get the same color of the rest of the piece, specially with the gold.
Regards. Adriana, in Santiago de Chile


#17

Dear Marilyn M. Smith

   If you do not glue the stone in what do you do with the epoxie.
I think that it would be hard to shape. Marilyn Smith 

You just form a seat for the opal and sort of cast it with the epoxy
(don’t know if ‘cast’ is the right expression - hope you understand
it anyway - English is not my mother tongue).

You can separate the epoxy from the stone either with a very thin
film of household plastic, if you do not want to glue it in place.

I used to do this but have now switched to putting a very thin
coating of oil or wax on the stone before it gets in contact with the
glue, but beware here - the fat stuff might spoil the epoxy.

By the way, when I visited Lightening Ridge, N.S.W. Australia a few
years ago I spoke to quite a few of the miners. Well, the miners here
also generally do all the lapidary, and I wanted to know why they
gave their pretty expensive stones such a shape, which was not very
’setter-friendly’ at all. They all replied that they got better
prices for the pieces if they were round and ‘cozy’ as if they were
made like ‘pharmaceutical tablets’. I tried to explain to them what a
nuisance it was to set an opal with a round back compared to an edgy
one, but they dit not care, - they simply got a better price for the
round ones. So, that’s life.

Kind regards
Niels L�vschal, Jyllinge, Denmark
@L_F8vschal


#18

I set my first boulder opal and chipped it. Any tips for a
newbie?


#19
I set my first boulder opal and chipped it.  Any tips for a newbie? 

First, don’t be discouraged. It’s very possible there were fractures
that made chipping almost inevitable. On the other hand, it’s more
likely that you just put too much pressure on the edge of the stone
when you were pushing the bezel in. What metal were you using? If
sterling silver or 14k gold, you really need to file the edge of the
bezel at the top at about a 45 degree angle to thin it so you don’t
have to push so hard. Otherwise, next time consider fine silver or
22k bezel wire that is 30 gauge. Also, how much metal were you trying
to push over the stone? The bezel need not rise higher than the top
surface of the stone (I’m assuming that the stone is relatively
flat-topped, like most boulder). That way, if the sides of the stone
slant in as they should, you will only need to exert inward pressure,
not downward. Hope this helps.

Beth


#20

joel - you may have missed the times i touted the best debonder in the
world made by uncommon conglomerates, inc. 1-800-323-4545. i just
loosen the bezel with an orange stick, drop in a little liquid
debonder - it takes a very little time to loosen any type of
adhesive: epoxy, cyanoacrylic, E6000, 527, everything. it does not
hurt pearls, ivory, opals, turquoise, lapis, malachite, metals, or
skin. there is also a tiny teeny little trade secret to assist anyone
else who may have to do work on them later: part of my signature on
the back of each piece is a tiny pinhole through which a wire can be
pushed when the adhesive has loosened.

anyone who has a problem with any of my suggestions - look around &
see if i am standing over you with a spitting oxy-acetyl torch
forcing you to do it my way! everything i suggest has been learned
from empirical study - no one taught me to do it a certain way, so i
have not gotten stuck in someone else’s rut. none of my suggestions
can get newcomers in trouble if they try them.

people, remember something: sawdust has been used for so long no one
has stopped to think that it started when there were no reliable
adhesives such as we now have. it is still used in 3rd world
countries where they have no decent adhesives. it is now the 21st
century - join it.

ive