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Store Opals


#1

I have a question about opals. What’s the best way to store opals.
I’ve looked at the Orchid archives and several opal web sites. All
I’ve found is conflicting Some say store opals in oil,
some say in water, some say neither. Are there any Orchidian opal
experts that can put this issue to rest for me. Thanks, Dolores


#2

Hi,

Never store opals in oil. The oil can get irremovably into cracks
and porosities and discolor with time.

Storing in water can do no harm.

I store my rough just plain ordinary dry; finished stones also. The
reason for that is some opals (notably Mexican, Ethiopian, Virgin
Valley very much so, and some Australian) can be unstable and crack
over time as their natural water content evaporates. A common
practise in cutting Mexicans for example is to leave the opal dry in
a warm place for several months to a year. If it hasn’t cracked by
then it’s likely to remain sound.(Likely, but not guaranteed.) So if
I store it dry and it stays sound that’s a good indication that it’ll
continue to do so and not crack on the customer’s finger.

Cheers,
Hans Durstling
Moncton,
Canada


#3

Hi Dolores, posted on this forum in the past (archives)
indicates that glycerin is the way to go.

Jon in Montreal


#4

Hi,

All our bar-coded opals are displayed on cards, and attached by
double sided tape. Which are then in plastic sleeves in a folder,
about 24 per page.

Or in a small gemstone container with the foam / felt backing type
of container for the more expensive ones.

Our rough opal is stored in heavy duty bags or metal tins, some even
in 44 gallon drums.

If its cut and a smaller parcel of it, its stored in a small snap
lock bag.

We do have some in a flask full of water, but this is more for
display because the water brings out the colours a bit more.

Regards,
Paul De Audney
Australian Opal Cutters Pty Ltd


02 9261 2442
Level 11, 250 Pitt Street
Sydney, Australia


#5

Dolores,

For some reason there is more mis-in the public domain
about opal than any other gemstone. Beginning with the idea of the
gem being a harbinger of bad luck. Some say that the “bad luck” rap
is the result of lapidaries who simply did not want to work with the
gem because of its tendency toward brittleness it was “bad luck” to
cut.

At any rate it is brittle and it also contains a small amount of
water - somewhere between 3-6% on average. So what’s all this stuff
about oil? Well a bit of oil smoothed on the surface of an opal
that has been abraded with wear will tend to brighten the stone
temporarily by filling in the tiny scratches caused by dust of a
period of time. Opal is generally below 7 on the mohs scale though
it can be as hard as 7.5. The problem is dust, which is quartz and
therefore will scratch of slightly abrade the surface giving the
stone a foggy appearance over time.

If I were planning to store an opal for a long period in a bank
vault I would probably immerse it in water. Why?, because vaults
are often dehumidified, it keeps the money from getting moldy. This
sort of environment could, over time, suck the water from the opal
dulling the play of color and/or causing it to craze.

Hope this helps.
Richard

Review Richard Wise’s new book: Secrets Of the Gem Trade; The
Connoisseur’s Guide To Precious Gemstones: www.secretsofthegemtrade.com


#6
Some say store opals in oil, some say in water, some say neither 

Delores,

Opals contain a small amount of water as part of their structure,
but it’s bound physically, not chemically, like water in a sponge.
So in cases where opals have a higher water content, some can be
prone to cracking or crazing if they dry out. This tendancy is
generally related to the location the opals came from. Most
Australian stones are quite resistant to spontaneous crazing, since
the water content is not high.

Some, like Idaho opal, are so high in water content that it’s almost
impossible to cut a solid stone and expect it to survive any length
of time without crazing. (These can be used to cut triplets
instead). And some, like mexican fire opal, falls in between,
meaning some will crack, others will not.

If you store opals in water, then obviously while they’re in water,
they won’t dry out. But this won’t restore opals that have started
to dry out, nor prevent future problems. Most folks using the stones
store them in air, in either stone papers or other sorts of displays,
or zip locks, or whatever. The main thing is to store them in decent
conditions. Don’t put them in a sunny window display case where
they’ll get hot, for example. But other than that, no special
measures should be needed. Among other things, in the event that an
opal is going to craze, it would be better that it happens while it’s
in your inventroy still, rather than after some customer buys it and
then is dissatisfied with your merchandise. So having the stone in
your inventory for a while can be viewed as proofing the stone…

You read now and then about storing opals, especially loose ones, in
oil. You can do that if you wish, but all it does is get them oily.
Doesn’t protect them, and can, if the oil isn’t clean, penetrate
matrix areas or cracks, carrying in dirt or whatever, and once it’s
done that, you’ll have a hard time cleaning it.

One thing sometimes used, that is very much NOT a good idea, is
glycerine, which one other poster, I notice, actually suggested.
Glycerine is hydroscopic, meaning it strongly attracts water.
Storing a stone in glycerine is about the same as putting it in an
extremely dry desert environment, and maybe worse. That’s just
begging the stone to dry out and craze.

46or my part, I figure this is a gem intended for use in jewelery,
which I expect my customers to be able to store and use in a normal
manner. So that’s how I store my stones as well. Mine are in the
little plastic foam filled gem boxes. Any that don’t survive are
either recut or tossed. Not many have met that fate over the years,
and I’ve had some, obviously poor sellers, that have been in that
display case for over 25 years, with no trouble other than the fact
that I’ve not made money off of them…

Peter


#7
    Hi Dolores, posted on this forum in the past
(archives) indicates that glycerin is the way to go. Jon in Montreal 

On the other hand, I have heard from several experts that one should
definitely not store opals in glycerin.

margaret


#8

Delores, To add just a little of what Peter says…

When you purchase opal, you should look at the stone two times. One
when it is dry and when it is wet. The first look will allow you to
see the actual surface of the stone to determine if it is pithy,
crazed, how the matrix boundry meets with the opal (a good indicator
of how solid the opal is) and, if held up to the light, where the
color goes…if it is straight banded, curved, slanted, etc, and if
there are internal flaws or inclusion. This is possible because most
opal is translucent and you can actually see into it. It may be
difficult to do this as most opal vendors display their opals wet
because…that is how you see the color. But it is important to
see it wet because this tells you if it is pin fire, harlequin, broad
flash, exactly what the colors are etc, etc. All this can affect the
value. Many vendors will allow you to dry a stone…many will not.
I would NEVER purchase from a vendor who will not allow me to dry a
stone for inspection. But, after all, it is my money and I’m not
going to spend it foolishly on a possibly flawed stone. Some
vendors, as Peter says, hold stones out of any moisture in an ambient
environment for a length of time before they put it onto the market
to insure it will not craze. Actually, there is a potential for ANY
opal to craze …one may take 24 hours another 240 years. It is
known however, that the more moisture it contains when it comes to
the surface, the quicker it will craze. (If I remember correctly)
Paul Downing says an opal with between 3-5% water is best and least
likely to craze.

I agree with Peter that opals should be kept away from oils. Hand
cream for example can have a yellowing effect on them…not the
colors but the matrix. Mineral oil can permeate cracks and widen
them (especially along the color layers where the microscopic silica
spheres change size/structure). Glycerin can actually suck the
moisture out of the opal.

When you do purchase an opal in water, simply take off the lid of
the jar and allow the water to evaporate. When the opal has been dry
for 6 mo or a year, check it for crazing. It none there, cut it.
Polish it all over…crown and base. The polish creates a hardened
and very smooth surface that keeps moisture in and contaminats out.

Well, I guess thats ‘little’ enough. Cheers from Don at The Charles
Belle Studio in SOFL where simple elegance IS fine jewelry!
@coralnut2


#9
    One thing sometimes used, that is very much NOT a good idea,
is glycerine, which one other poster, I notice, actually suggested.
Glycerine is hydroscopic, meaning it strongly attracts water.
Storing a stone in glycerine is about the same as putting it in an
extremely dry desert environment,  and maybe worse. That's just
begging the stone to dry out and craze. 

Thank you for correcting me on this Peter, I wasn’t aware that
glycerine would draw moisture from opals. Somehow this had stuck in
my mind from previous archived posts and I appologize for misleading
anyone.

Jon in Montreal


#10

One reason that one hears of storing opal in glycerine is that the
refractive index of glycerine is close to that of opal.