I’d like to share a few quote from something I recently read:
“Always immerse opals into a compound of mineral oil as these
stones will dry out and the result will be internal fractures.”
K Kelly
Kevin,
If you’re sharing this because it’s so wrong, I’d be interested in
knowing if the source is recent or from an old book or article.
If you’re asking should it be done: No! Please do not do that!! Not
unless it’s unstable opal you intend to keep in mineral oil for
permanent display like some Virgin Valley Nevada opal.
There are many types of opal, and each has differing percentages of
water as part of its structure. After it has been mined, stable opal
reaches an equilibrium after losing some water, and does not
fracture. “Cracky” or unstable opal, will show cracks throughout the
entire piece no matter what you do. Other opals, like Virgin Valley,
Nevada, or Mexican fire opal, may or may not crack, or they may
become stable after some trimming.
If uncertain about how to handle any given opal, rough or cut,
contact someone who works with it on a regular basis. If you don’t
know someone personally, please try here, or through the American
Opal Society. www.opalsociety.org
Carol
Carol J. Bova
The Eclectic Lapidary
http://www.eclecticlapidary.com
"Always immerse opals into a compound of mineral oil as these stones will dry out and the result will be internal fractures."
Absolutely not.
(No doubt there’ll be a hundred other posts to the same effect)
Opals can be microporous. Get oil in there it will in time yellow.
Opals contain 2 or more percent water as a natural constitutent;
some can dehydrate over time. Normal wear promotes rehydration.
Absorbed oil would hinder this.
A similar perhaps even more pernicious old wives tale is that opals
should be stored in glycerin. This as I understand it is downright
hygroscopic and may actively deplete the opal of its natural water
content.
Dessication can lead to crazing. Some types of opal are more prone
to this than others. Virgin Valley opal tends to craze almost the
moment it comes out of the (wet) ground. Mexican opal is somewhat
prone to crazing. A common and reccommended practise with Mexican
opal is to leave it in a hot dry place - on a radiator, in a sunny
window, or similar, for six months to a year before cutting it. If
it hasn’t crazed by then chances are it won’t. Australian and
Brazilian opal are about the most stable.
That slight percentage of water incidentally is also why it’s not
recommended to keep opals in a safety deposit box as these are often
climate controlled for extra low humidity.
Opal dealers do generally keep their rough in water but mainly for
visual effect.
If your cut opal is and has been in good condition the best practice
is to treat it gently, wear it often, and apart from that just leave
it be.
Cheers,
Hans Durstling
Moncton, Canada
K. Kelly and my fellow Orchidians
I once worked at a jewellery company who NEVER bathed their Opals in
any kind of oil or liquid to prevent cracking. So it was up to this
setter (me) to inspect EVERY Opal before being set. If I didn’t, it
was MY responsibility. The manager retorted; “Oh, we don’t need to do
this, our Opals are fine”, yeah sure, till they crack under heat and
dry conditions and who’s to blame?
Of all of their larger Opals that were never used too often, rest
assured most of them had hairline cracks in them, prior to setting.
Take this from Kelly and me, for these Opals of
wisdom…Gerry!
Hi, Just a short note on the effects of any oil on opal, it does
nothing its just another myth out there ,if opal is cracky it is
just that, and nothing you can do will stop it in the long run. The
only way to avoid this problem is to educate yourself as you would
with any other gemstone and try and deal as close to the source as
you can or build up a good client , customer relation with a
reputable opal dealer, quality opal is expensive and you will get
what you pay for. Australian opal is the most stable but there is
some very low grade problem material out there in the market place
sold by unscrupulous dealers and that is the case with all gemstones,
Once again its EDUCATION, EDUCATION AND MORE EDUCATION.
Bye
Christine from the Ridge where is summer is nearly here.
I once worked at a jewellery company who NEVER bathed their Opals in any kind of oil or liquid to prevent cracking.
Um, Gerry’ Some folks would consider that the proper way to do it.
Remember that soaking an opal in water won’t, with the exception of
rare hydrophane opal, actually replace any dried out water content
*(the cause of crazing in some opal). Obviously, while an opal is
under water, it won’t dry further, but that protection ends the
instant it’s removed from the water. If the opal is of a type prone
to crazing, soaking only prolongs the wait until it happens, and
delays the effect only by the amount of time the thing is immersed,
no longer. Not much protection. . Some of us might suggest that it
would be better to find this out about an opal while it’s still in
the jeweler’s or opal dealers hands, before it gets sold to a
customer who’ll then be unhappy. I know several opal cutters who
routinely put newly cut stones just into storage in their safe, nice
and dry, for months or even a year or so, figuring that this way,
any stones prone to crazing will do it before being sold. Weeds out
the bad stones…
And oil’ All that does is get it oily. It won’t even completely stop
the drying of the opal, though it will slow it. And again, the effect
is only while the opal is actually immersed. A thin film of oil won’t
stop it from dehydrating, if it’s an opal prone to that problem,
which not all are. Now, I’ll grant one benefit from oiling an opal.
If the stone is a bit scratched up and scuffed, a little oil wetting
the surface may make it look a bit shinier. But repolishing it would
be a better treatment for this problem.
Some writers have suggested that a much better protection for opal
is a really good polish, as this is thought by some to tend to seal
the surface some. I tend to doubt this, but I’d give it more credence
than water or oil soaks.
Old wives tales die hard. But I’m a bit surprised to see you still
quoting one. This is simply a case of traditional lore that’s just
not useful in the real world. Check any of the available professional
level gemological literature on opals if you doubt this.
Peter Rowe
Then I’m really confused, because that was the exact advice put out
in Lapidary Journal some time ago-there was an issue discussing the
photography of opals, and in that article they said to do that.
Which is what I did with some opals in raw form that I have.
So now what?
Miachelle
...quality opal is expensive and you will get what you pay for.
Unfortunately, this ain’t necessarily so. I’ve had some pretty
expensive stones that cracked just the same. That’s why I generally
keep opals for a year or more before I set them.
I like to say, you don’t necssarily get what you pay for, but you
definately don’t get what you don’t pay for.
Is it a sign of being over the hill when you start quoting yourself?
–Noel
If you're sharing this because it's so wrong, I'd be interested in knowing if the source is recent or from an old book or article. If you're asking should it be done: No! Please do not do that!! Not unless it's unstable opal you intend to keep in mineral oil for permanent display like some Virgin Valley Nevada opal.
My posting was meant as a provocation because it’s so wrong. It’s a
quote from a book from an author presenting himself as an expert
I’ve been cutting opal for about 25 years of and selling opal in
jewelry retail for some fewer years. I’ve heard more nonsense about
opal than any other material. Perhaps it’s because opal is so
mysterious and displays such a wonderful variety of colors that it
attracts fanciful stories and has had legends grow up about it.
One example: an intelligent woman said she was concerned about
buying opal earrings because she heard that if she went from a warm
room to a colder room while wearing the earrings that the opal would
fracture. This was from a well educated person.
I started cutting really low grade opal because it was what I could
afford. When I started out dealers often sold material in bottles
containing gylcerine. The R.I. of gylcerine is close to that of opal
and will cause any fracture to disappear. If you buy rough opal, buy
it dry. Water or other solutions are disguises.
Finally, good opal is good opal. I can’t remember any piece I’ve
cut, in recent memory developing fractures or crazing. Actually I
attribute my luck to a discerning eye and reliable dealers when I
buy the rough.
If you read something that know to be wrong; what do you do? Is it:
“If you can’t say something nice, don’t say anything.”?
Kevin Kelly
Exactly for photography yo can oil opal to show color flash better
me I do not alter what my client will see with their naked eye just
my personal preference
teri
An American Cameo Artist
www.cameoartist.com
Then I'm really confused, because that was the exact advice put out in Lapidary Journal some time ago-there was an issue discussing the photography of opals, and in that article they said to do that. Which is what I did with some opals in raw form that I have. So now what?
Mineral oil is fine, if you wish, for storage of uncut opal rough.
Won’t prevent or in any way affect future crazing of the opal, but
won’t hurt it either, in MOST cases. Some opal might absorb some
oil, but most won’t. And oiled opal looks wet, which with rough, can
help you see the colors. So it’s great for photography, giving you
time to set up the shot without the opal drying off as it would if
you were futzing around with just wetting it with water under photo
lamps. But make no mistake. Oiling the opals is just a storage
stopgap, not any sort of real prevention for crazing or treatment for
it. For photography, though, it makes a lot of sense to me. The
argument against oiling ROUGH opal would be that a small number of
stones might absorb some oil and could discolor, and that by storing
rough in a way that tends to prevent crazing, you’re only increasing
the chances that stones you eventually cut from the rough will end up
crazing, wasting your cutting time. Stored dry, if it’s going to
craze before you get around to cutting it, then at least you’re not
spending time cutting the stuff if it’s going to craze later anyway.
Peter
I can only say amen to everything Peter has said about oil and opal.
The play of color in opal is the result of water vapor in the tiny
gaps between round collodial spheres that form the structure of
opal. Think of the gaps when pool balls of equal size are put
together in a rack. The four round surfaces do not quite match up
leaving a tiny diamond shaped gap. The actual color is dependent on
the size of the spheres which dictates the size of the gap between
them. The oil myth comes, no doubt, from the fact that a bit of oil
when rubbed on the surface of an opal that has been abraded over
time by the dust in the air, will mask the tiny abrasions and
restore, to a degree, its former play of color.
Opal that is mined in wet fields has a tendency to craze simply
because it never really had the opportunity to become stable through
a drying process that takes many milenia.
I have only had one parcel of black opal that crazed but opal will
do some odd things. I bought a parcel of boulder rough from a
Yugoslavian miner in the Queensland outback and had it cut in
Winton. There were two pieces of opal in matrix, firey veins that
ran through the ironstone matrix. One, I set and sold and within a
week the client brought it back. All the color had turned to white
potch. This is called “cottoning”. The second piece cut from the
same rough, I kept for several years and it remained as bright and
colorful as the day it was cut.
Usually, if unstable, the opal will craze fairly quickly. If you are
buying from an honest dealer he will normally take back any stones
that craze.
Richard
www.rwwise.com
For Information and sample chapters from my new book:
Exactly for photography yo can oil opal to show color flash better me I do not alter what my client will see with their naked eye just my personal preference
Are you saying that you personally oil opal for photography? Or
not?
I may be off course here but has anyone tried the stuff they use to
repair chipped windshields with? Its a kind of very thin epoxy I
think which seeks out and fills even the tiniest of cracks. I would
think that this may strengthen the opal and seal the edges where any
further water can escape from.
Best Wishes
Ian
Ian W. Wright
Sheffield UK
I am saying I do not oil for photography Or any other reason. If I
wish to see a bit of opal rough better I wet it with water which
does no harm no foul before I cut into it and at times I use a baby
food jar of water and a true light to view it to see how I wish to
proceed. I buy opal rough from miners for carving and get all kinds
of stuff 
Teri
An American Cameo Artist
www.cameoartist.com
Ian,
I don’t think there is anything that will stop an Opal from crazing
if that is what that Opal was going to do anyway.
As for the windshield material, I am not familiar with what they are
using but some gem cutters use a material called OPTICON which does
exactly what you were referring to. It fills even the thinnest of
cracks in a gemstone.
If anyone uses this material or any sealer or filler material please
be sure to disclose this when you sell the Gemstone.
Greg DeMark
email: greg@demarkjewelry.com
Website: www.demarkjewelry.com
Custom Jewelry - Handmade Jewelry - Antique Jewelry
Peter I always read your posts with great attention and am better
informed as a result. I must ask this: On the particular question of
photographing opal are you speaking from personal experience?
In my experience of photographing opal If the opal is properly cut
and polished it doesn’t need any enhancing for photography. That
being said, I’ve found opal the most difficult stone there is to
photograph. I’ve given pieces to professional jewelry photographers
to shoot, with poor results and at considerable expense.
Photographers I’ve dealt with seem to be looking at the metal and
ignoring the stone as do show jurors.
[An aside: it annoys me to no end that when appling to juried shows I
get no credit for the lapidary work. Is lapidary less skillful than
metal work in jewelry? There usually is a separate metals category;
jewelry is often a combination of metal and stone.]
But I digress. Back to the photography: As a result of my experience
with photographers I’ve learned to do it myself. Since I cut the
opal I’m more familar with it’s qualities and color than the
photographer who tends to ignore the stone and ignore the fact that
it must be lit differently than the metal.
I once had an offline conversation with David Barzilay about
photographing opal suggesting that he take two shots of the same
piece, lighting the stone differently, mask the stone in the shot
made for the metal and paste in the shot made for the stone. One
must have perfect registration for this to work. This method works
beautifully for all stones. Photoshop of course.
Mineral oil is fine, if you wish, for storage of uncut opal rough. Won't prevent or in any way affect future crazing of the opal, but won't hurt it either, in MOST cases.
This thing about oil and opal perpetuates a fiction. Some don’t want
to pay the price and try ways to make the opal rough they buy better
than it is by oiling epoxying, etc. Perhaps the “silk purse from a
sow’s ear” metaphor applies here. Often buyers don’t want to pay the
price for quality material. Opal is the most expensive stone in the
world except for fancy colored diamonds.
I can’t recall a piece of rough crazing for any reason; I attribute
this to buying quality from knowledgeable dealers. I live at 6850
feet elevation in NM, beautiful but very dry (yesterday 12%
humidity). All my opal is stored dry. I’ve not had a problem.
For those who want to pursue the matter of play of color in opal and
other opal matters: “A Field Guide to Australian Opals” by Barrie
O’Leary is a fine reference.
Kevin Kelly
PS
my reference to Barry O'Leary's book might be misconstrued. I
didn't intend it to be a comment in any on Mr. Wise's book
which I haven't read. Mr O'Leary's book on opal is very through
and was one of the first serious books on opal that I
encountered.
Kevin,
One comment within your reply to the wonderful Peter Rowe touched
me.
An aside: it annoys me to no end that when appling to juried shows I get no credit for the lapidary work. Is lapidary less skillful than metal work in jewelry? There usually is a separate metals category; jewelry is often a combination of metal and stone.
I am also a member of USFG Faceter list. I have long asked them why
the cutter is never given credit in the sale of jewelry. Same as you
Lapidary comment. If the jewelry is sold under the name of XXX, then
it is only right YYY be listed as faceter. Of course if it is
lapidary work, that too deserves attention and mention.
IMHO
Terrie