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Advice on setting opal


#1

Hi all,

I have been asked to set a small opal (15mm by 8mm) into a sterling
silver bezel mount as a pendant. I know how to make the bezel setting
but I have never set an opal before and I have a few questions to
clarify before I set the opal:

  1. Some of the discussion I have read recommend having a black
    background inside the bezel to enhance the play of colours in the
    stone. Apparently some people use black pigmented epoxy resin. I am
    not particularly keen on using epoxy on a $150 stone and I wondered
    if I could blacken the inside of the bezel cup with liver of sulphur
    to serve the same purpose?

  2. Given the notorious fragility of opal, when I make the bezel is
    it better to make it a snug or slightly loose fit?

  3. I presume I should complete the polishing of the mount (except
    for a final hand polish) before I mount the stone. Is this consistent
    with other people’s experience?

  4. Do I need to take any particular precautions beyond the usual
    when rolling over and burnishing the bezel strip particularly given
    the rather tight curves?

Any advice would be greatly appreciated.

All the best
Jenny


#2

Hi Jenny,

You have two options to consider, you can use liver of sulfur to
blacken the inside of the bezel just first place the opal on a black
back ground to see if the stone has more fire as a result. A lot of
jelly opals have fire, but have to be positioned to see it. I’ve cut
the back out of some settings and left a small rim so that when the
stone is put in the bezel light passes thru. This now affects the
opal color by what clothing is worn under the stone. When setting the
stone you don’t want to have a tight fit as opals are very soft. I
sometimes use a separating disk and measure around the bezel in equal
spaces then cut slots in the bezel wall, this way you can get a
perfect fit because pushing the bezel becomes very easy to shape
around any curve or corner.

Good luck


#3

Do not use the epoxy unless you have to. If any thing back the opal
with a piece of black onyx or black jade for strength. If you are not
a stone cutter you can get an epoxy call JB Weld in the dark gray
color, it is available in auto parts stores and in some home
improvement stores. It is a metal base epoxy and sets hard and it is
used to back turquoise also. Opal is a finicky stone, is it white
based and opaque or is it semi translucent with a strong color play
in a crystal type body, crystal you can see through and tends to be
tougher then regular white based opal. make you bezel with dead soft
silver and leave some play or loosely fit. One thing to take in
account is the opals edge or girdle, it might be rounded, slightly
round on the bottom, flat bottom and a sharp edge, flat bottom
slightly rounded edge and a low dome top with more opal on the
bottom. Sorry to go on but I cut opal and do custom work and have set
hundreds of opals. The biggest mistake people make with opal is
getting part of the stone in a bind or pinch, this will cause a
tension crack or chip and the outcome unpredictable. If all is done
right make sure you piece is well secure and take a bezel roller and
ease the bezel down evenly going around slowly matching positions as
you go around not all at one roll. Silver is very workable and should
go down smoothly just do not use to thick od bezel wire. One last
thing is the choice in bezel wire and is it going to be completely
closed on the back? I prefer no shelf on the bezel wire and soldering
on a sheet of silver and trim excess form the outside. Just remember
do not stress the opal and it wise to do a compete polish before
setting and as little handling as possible after set and if you have
to remove scratches on the bezel after set pumice is a good choice
incase you hit the opal with the wheel. I hope this helps.

Carl


#4

jenny -

there are so many different methods for setting stones but i have
used the same tried-and-true-never-cracked method since i started
cutting and setting opals. first, opals probably got their bad
reputation from old jewelers who put them into prong settings -
opals are about 2% to 24% water - the pressure of prongs was a
disaster waiting for a wrong move by the wearer. knowing there was no
way even the conscientious wearer could avoid some contact/vibration
wearing an opal, i started adding a thin layer e-6000 adhesive in the
bezel - there has never been a break or crack since - (the adhesive
sets without hardening and absorbs little shocks) and i tell every
buyer to let me know about any problem with every piece of my work.
as to the backing, usually i cut a very thin slice of lapis, trim it
to fit the stone back, add a little more adhesive and set in the
opal. to save on rolling over the edge of the bezel i always
’feather’ the bezel top edge by grinding it so it is tapered -
thinner at the top - and easier to roll and burnish with a lighter
touch. if you continue to work with opals you will be amazed at how
accomplished you’ll feel. when you polish an opal, touch it to your
chin every few seconds to keep the crack-causing temperature down -
to remove stone from the dop stick wax, put it in the freezer for an
hour or so and it falls off. just don’t take advice from 'experts’
who say to start cutting opals with low cost material to learn -
don’t! - instead use a decent grade of opal rough! what is the reward
of cutting and polishing inferior opal rough that doesn’t have the
same ‘fire’ properties as good material and ending up with an
inferior stone?

good luck -
ive
people, think more now, regret less later.


#5
  1. Some of the discussion I have read recommend having a black
    background inside the bezel to enhance the play of colours in the
    stone. Apparently some people use black pigmented epoxy resin. I am
    not particularly keen on using epoxy on a $150 stone and I wondered
    if I could blacken the inside of the bezel cup with liver of sulphur
    to serve the same purpose? Answer: If the opal is translucent or
    transparent it can benefit from having a black background.

If it’s not, then it won’t do much. Black epoxy can work, but a
better solution would be to use bit of plastic polyethylene (like a
butter tub lid) cut to fit the bezel cup and painted with a couple
layers of little black enamel paint (Testors model paint is good).
Sometimes two layers of plastic is good., especially if the stone
benefits from being lifted a tad relative to the bezel height. The
plastic will provide a little “give” when you press down on the
stone, so there is less chance of cracking it. The enamel holds up
pretty well to moisture which will inevitably work it’s way into the
setting. I would not recommend liver of sulfur. It will continue to
oxidize and the same exposure to moisture will eventually lessen the
look. Besides LOS is not black, it’s only dark grey.

  1. Given the notorious fragility of opal, when I make the bezel is
    it better to make it a snug or slightly loose fit? Answer: I always
    prefer a tight fit. You don’t want the opal rattling around in the
    bezel. The use of the plastic under the stone helps a lot. However,
    “tight” does not mean “crushingly hard” pressure with the burnisher.

  2. I presume I should complete the polishing of the mount (except
    for a final hand polish) before I mount the stone. Is this
    consistent with other people’s experience? Answer: Not only for
    opals, but any stones, setting the stone is always the last thing
    one does, other than a buff with a Sunshine or other cloth.

  3. Do I need to take any particular precautions beyond the usual
    when rolling over and burnishing the bezel strip particularly given
    the rather tight curves? Answer: Use the plastic under the stone and
    start on the tighter curves first, pretty much like any cab. With
    instances of very sharp curves on cabs I have sometimes simply
    notched or cut out a small section of the bezel wall so that the
    metal doesn’t bunch up there when turned over. There is no rule that
    says a bezel must run completely around the stone, unbroken. I think
    a gap looks nicer than a crunched bezel. I do this frequently on
    square or triangular cab corners. Opals are not nearly as difficult
    to work on as some people seem to make out. but then I generally
    don’t work on $10,000 per carat opals.

Denny Turner


#6

I also have an opal to set. So any I will echo Jenny, any advice
will be appreciated.

Thanks,
Jane


#7

How high your bezel is will have an impact on just how you set it.

If the bezel is high and the stone has a shallowish dome it would be
problematic to try to cinch the bezel by bending the base first and
then working higher. What you might wind up with is a bezel top edge
that just won’t go down that last little bit because you’ve work
hardened the rest of it. You run the risk of putting too much
pressure on, trying to close the gap. So maybe bring the edge in some
first and then work your way down the bezel.

I’m assuming this is an oval. Start your rocking at the apex of the
small radius. Now you’ve got the large radius sides in which to
smoosh the bezel. Doing it the other way concentrates stress at the
smaller circumference which leads to puckers or worse.

I’d be leery about using any black that has a gloss to it. You might
get funniness, like blinking.

I won’t get into the ethics of a black background to enhance the
stone. If you do it make sure its permanent. Black paper won’t cut
it, imo.


#8
I also have an opal to set. So any I will echo Jenny, any advice
will be appreciated. 

I have been reading all that “sage” advice on setting opal, and I am
strongly advice to to ignore it.

There is a difference between been a goldsmith, or been a jewellery
hack. Goldsmith never uses adhesives of any kind. Gemstones are never
darken or lighten, or painted, or enhanced in any way. Gemstones are
never backed up with anything. If gemstone cut too thin to withstand
normal setting process, it should not set at all. If gemstone lacking
in natural appearance to stand on it’s own, it is not a gemstone, but
a rock and should not be used in jewellery.

With that in mind, we can talk about setting opals. First, precious
opal is alway cut with sufficient thickness. Thinly cut stones are
always a suspect of treatments, so only work with properly cut
stones.

Only select stones with water content less than 7 percent. How can
one know? If you work with a lot of opal, invest in hydrostatic
balance. As an alternative, most of school labs have them, your local
appraiser guy should, and etc. Opal density should be 2.15 or higher.
You also would need a polariscope. They are not expensive. Opals are
amorphous, but internal strain is commonly present, which manifest
itself as ADR ( anomalous double refraction ). Presence of ADR, by
itself, is not a deal breaker, but if pinfire opal displays strong
ADR, this is a warning sign. One looks for discrepancy between
pattern and presence of strain.

Assuming everything checks out, it is time to set our opal. Securing
stone in the setting must be the very last step. No polishing,
ultrasonic, steaming should even be contemplated. Choice between
bezel and prong is matter of preference. Opal can be successfully set
in prongs. Whatever method one choses, setting should be constructed
from 22 karat gold, or higher. Stone must fit into the setting so
that after mere placement, it can be lifted only with great
difficulty. That does not mean stone is pressed into setting,
absolutely not. Stone should settle under it’s own weight. After
stone is fitted, only slight displacement of metal is required to
secure the stone.

Leonid Surpin
www.studioarete.com


#9
opals probably got their bad reputation from old jewelers 

On a more generic, stone setting vein… Opal is a breeze, try
setting a peridot sometime! There is opal and then there is
opal… I suspect that the OP’s stone, at $150, is likely your
standard white opal cab. Those can be set easily with standard care

  • good fit, no pressure points, etc. Some opals are flat topped -
    opal matrix, for one. I’ve been setting some lately that have a sort
    of grain that can come out if abused. Like gravel that’s stuck
    together, vaguely. And always there can be cleavages and such, to be
    looked out for.

The only real problem with a solid white opal is pressure points or
outright mistakes. If you put too much pressure in the wrong place
or if a steel tool skips across one, they can easily chip. Just
don’t do that…

I remember setting a large, expensive emerald in prongs long ago.
So, I was pushing on this prong, and as I did I watched a cleavage
open and closee very time I pushed -“Go ahead, watch what
happens…!” Nothing happened, in the end. There’s a wide variance in
stone properties, but stones I would put as worse than opal to set
would be: Peridot - don’t ask me, and you WILL pay for breakage…
Emeralds can be not so bad or very, very bad.

Genuine topaz, kunzite, tanzanite and anything quartz, like
amethyst.

Good, solid opal isn’t so bad to set, it’s mostly reputation and
yes, you need to be careful. Agate it’s not… BTW -We went to a
Lalique show and there was a very famous piece with a huge opal. You
can’t see it in the pics, but you can see it in person - there on
the back of the stone was black paint, partially peeling off…


#10
opals probably got their bad reputation from old jewelers 

On a more generic, stone setting vein… Opal is a breeze, try
setting a peridot sometime! There is opal and then there is
opal… I suspect that the OP’s stone, at $150, is likely your
standard white opal cab. Those can be set easily with standard care -
good fit, no pressure points, etc. Some opals are flat topped - opal
matrix, for one. I’ve been setting some lately that have a sort of
grain that can come out if abused. Like gravel that’s stuck together,
vaguely. And always there can be cleavages and such, to be looked out
for.

The only real problem with a solid white opal is pressure points or
outright mistakes. If you put too much pressure in the wrong place
or if a steel tool skips across one, they can easily chip. Just
don’t do that…

I remember setting a large, expensive emerald in prongs long ago.
So, I was pushing on this prong, and as I did I watched a cleavage
open and close every time I pushed -“Go ahead, watch what
happens…!” Nothing happened, in the end. There’s a wide variance in
stone properties, but stones I would put as worse than opal to set
would be: Peridot - don’t ask me, and you WILL pay for breakage…
Emeralds can be not so bad or very, very bad.

Genuine topaz, kunzite, tanzanite and anything quartz, like
amethyst.

Good, solid opal isn’t so bad to set, it’s mostly reputation and
yes, you need to be careful. Agate it’s not… BTW - We went to a
Lalique show and there was a very famous piece with a huge opal. You
can’t see it in the pics, but you can see it in person - there on the
back of the stone was black paint, partially peeling off…


#11

Hi all

Thanks for all the useful advice. I have now successfully set the
stone in a .925/100 bezel mount. I found the stone looked best
against a silver rather than black background because it then
displayed booth its fire and an inner pink glow. It really is a
lovely stone. I left a little bit of play in the mount and gently
eased over the edge of the strip to hold it securely in place without
putting any pressure on the stone. The plain mount works well in
drawing attention to the stone itself rather than the mount.

All the best
Jenny


#12

Hi Jenny, The black backing works best if it is ON the back of the
opal, so some use flat black spray paint, black epoxy, or whatever.
Using a darkener in the bezel cup would be better than nothing, but
it won’t be as black, and it doesn’t work as well. If your opal is
white based, I would use the blacking, as it either wont do anything
or it might give the stone a strange bluish tint that really doesn’t
look to good on white opals (IMHO).Make sure the opal has a small
bezel on the back edge (it should if it has been correclty cut)I
have only ever cracked an opal during setting maybe 3 times, and all
three times it was because I tried to put the stone in the bezel cup
and it didn’t quite fit but I thought it was so close that I could
just push a bit and it would go in. Bad idea! Make sure the stone can
just drop in completely to the bezel cup and you should be fine. Set
as you normally do.


#13
Make sure the opal has a small bezel on the back edge (it should if
it has been correclty cut) 

Make sure it has a" beveled" edge around the bottom edge of the opal.

I use back backing when the metal changes the base color of the opal
by reflection of light passing through the opal. Crystal opal will
take on a yellowish color. My opinion is that using gold colored
metal as a backround is is no different than using a black backround
as far as changing the natural color of the opal. Put an opal on a
black backround or use a black permanent marker and see if the colors
stand out more. If there is no change, don’t do it.

Put it on a silver or gold backround and see if the body color
changes or if the colors look better, worse, or no change. I would
suggest using this as a basis for your decision. My opinion is that
using a black backround is not to deceive unless the opal is being
misrepresented as a black opal. Disclosure that a black backround was
used to bring out to enhance the colors of the opal takes care of
issue of deception.

I have shown customer how their opal would look with a black
backround and they always choose to have the backround black.

Richard Hart G.G.
Denver, Co.


#14

Black nail polish in the bezel cup works really well.


#15

As a general principle I don’t like anything that alters the stone
itself. I’ve watched someone else set a moonstone by first using a
piece of black plastic trash bag cut to fit in the bezel, then
putting the stone on top of the plastic - voila! Your dark background
without altering the stone, fast, easy and cheap.

Mary Partlan
White Branch Designs


#16

… Sorry, I did mean beveled, not bezel. Interesting discussion, as
common practice is to use flat black backing, as it absorbs reflected
light, emphasizing the refracted light from the opal. But I can see
that using a different colored backing could be interesting too. I
have sometimes thought that the black backing made some opals
look “cheap” if the color was not strong enough to begin with.


#17

Hi re opals I use triplets, doublets and solids. My understanding is
that a triplet is 1% of the value of the SAME material if it was a
solid opal. Also the triplet SHOULD look fantastic if it does not do
not buy it. Also NEVER get a triplet wet it will delaminate and do
not get ANY opal hot it will crack. If the customer wants you to set
their sentimentally precious stone why not? I have even seen baby
teeth set in necklaces worthless to you and me but priceless to the
parents.

Richard


#18

Look, if you back a stone with an artificial color, whether you
attach the artificial color to the stone or not, you are still
altering the color of the stone. And you better disclose it.
Otherwise any cheap S%#t stone can be backed with colored plastic and
heck, might as well not use the stone at all.

Why you guys think it’s okay to pull this crap with opal, I don’t
know. Remember, you are not just working for the client, but for the
owners that come after the client. How the heck would you like it if
you bought a piece of jewelry for the stone, wanted to have the stone
set in a different design, only to find out that that stone was crap?

One of the reasons I hate the jewelry industry has to do with the
way some jewelers, or companies, mislead the public then it comes to
Gemstones. I think there should be standards in gemstone
nomenclature. “Fire Opal” should not mean “Precious Opal” for
instance. So a jelly opal with a black marker back should be called
"black marker opal" if not “fraudulent”.

A lie is a lie, even in this industry!
TL Goodwin


#19
Look, if you back a stone with an artificial color, whether you
attach the artificial color to the stone or not, you are still
altering the color of the stone. And you better disclose it. 

TL, while I’d agree that actually altering a stone is something that
should be disclosed, I think you’re carrying this concept way too far
here. There is no particular reason why the metal underneath a stone
has to be some specified color or other. That’s up to the jeweler. If
I use oxidized silver, or bright polished gold, or bright polished
silver, or open air, under an opal, or any other transparent or
translucent gem for that matter, is independent of any alteration to
the stone, but rather is a design decision for the jeweler to make,
needing no more disclosure than any other aspect of the metal or
design. Usually, any competent jeweler or even most knowledgeable
jewelry consumers both understand this, and can usually see what’s
been done. For that matter, even an opal with a painted on black
coating, or a black glue behind it, doesn’t actually look like a
black opal. If you know opal at all, you can easily see that it’s
simply a white opal where the black color behind makes the play of
color (which does have to already be there, after all) stand out
more. Calling this method automatic deception is going a bit too far,
I think, though I’d agree that it’s best to let a customer know, just
to be sure.

But simply choosing a mounting style or method that will be most
attractive for a given stone is just part of the jewelers job, not
some automatic attempt at fraud should that design not fit your
preconcieved notion of how the stone should be set.

Yes, if I paint the back of an opal, or glue a black back to it, or
glue it in with black cement, that I’ll agree is something a customer
might deserve to know. That’s actually changing the stone itself. But
oxidizing or darkening the metal behind a stone? No, that’s not
altering the stone itself, even if it does cause some of the same
change in “presentation” appearance of the stone. That simply is
neither dishonest, nor any attempt at fraud. It may be an attempt to
get the stone to look it’s potential best, but that isn’t fraud
either. Selling a doublet or triplet as a solid opal, THAT’s fraud.
Selling a dyed stone as natural color, THAT’s fraud too. But please.
somewhere there is a line between properly setting and most
advantageously displaying, a stone, versus actually altering the
stone. Don’t confuse the two.

Just my two cents.
Peter Rowe


#20
I think you're carrying this concept way too far here. There is no
particular reason why the metal underneath a stone has to be some
specified color or other 

Actually there is a very good reason. Let’s recall definition of a
gemstone. In order to call a mineral gemstone - mineral MUST posses
BEAUTY, RARITY, AND DURABILITY. If any of it missing, it is not a
gemstone anymore.

By using techniques like shading, backgrounding, and any other
technique which creates any of the three cardinal gemstone
properties, we creating gemstone appearance without a gemstone.

I suppose that with proper disclosure it may be ok, but such
practices are very rarely disclosed and for the good reason. Nobody
in his/her right mind would want to pay for that type of jewellery.

Leonid Surpin
www.studioarete.com