I started this thread inadvertently in a discussion of Peruvian
turquoise by saying that opal is a stone that can crack
spontaneously. The discussion has certainly come a long way since
that simple statement. Although I stated that opal can crack or
craze (same thing) I didn’t say it happened all the time and I don’t
believe it does. I have a lot of opal of many different kinds,
though mostly Australian, that has not cracked over quite few years
and it was dry for many years before that.
However, one thing that’s obvious is that there is so much wildly
conflicting about opal that I don’t believe anyone knows
for sure. I’ve heard some rather wild and wooly stories about opal
for people who are considered major experts. I suspect there are too
many variables to start with and then there are multiple
superstitions and old wives tales and just plain stories that are
passed along from one person to another of through books repeating
some of those stories. I’ve often thought that there was more
misabout opals than just about any other stone and
there’s a heck of a lot about other stones too.
But there are some things that are fairly clear. I keep my rough
opals in water so that, when I’m looking for something in
particular, I can see them more easily. When the surface is rough on
a stone, it’s hard to see what it actually looks like internally.
Obviously, the water temporarily smoothes the surface.Once they’re
cut I keep them dry. I live in Vermont where there’s a fair amount
of humidity so I don’t think they dry out much. I do believe they
tend to be more susceptible to damage from heat than a lot of other
stones. And they don’t like shock much either. That’s why it’s
recommended that they not be put into an ultrasonic cleaner.
I think there are two factors of water in opal. If the stone is
porous and some are more porous than others, then the opal absorbs
water. Those stones will release that absorbed water when kept dry.
But I think there is also water molecularly bound in the stone that
stays in it. So whereas the chemical composition of quartz is Si O2,
the composition of opal is Si02 H20. I’m not a chemist, but I don’t
believe that changes easily. Just like you don’t separate hydrogen
and oxygen in water very easily. Incidentally, to show how
mysterious opal can be scientifically, I don’t believe anyone has
yet figured out what make black opal from say Lightning Ridge,
black. If someone knows, please pass it on.
So it seems like the opals should be dried for quite a while before
cutting to ensure that the absorbed water, if there is some, is
dried out before cutting. If so, the opal ought to be stable.
I think too that when cut, there are internal stresses in the stone
and they may change due to removing materials from the outside.
Changing the levels and planes of the surface will create new and
different surface tensions and stresses, though I’m not entirely
clear about this. However, another example of this sort of change is
with wood. Anyone who’s ever worked with wood knows that cutting it
and changing it’s shape will allow changes in the stresses and it
can crack and check after being worked. That’s just the nature of
it. Yet people still use it for making furniture and houses and
other stuff the last time I looked even though the joints in the
wood can loosen with time and the nails and screws holding it
together can rust.
Besides that kind of phenomenon, there are lots of jewelry materials
as well as other stones that change over time. Pearls can certainly
dry out as can any shell which will probably not do well exposed to
sunlight long term. Many stones have serious cleavage issues like
topaz, or are really too soft for some applications. I’ve heard from
many people that tanzanite is too soft for rings. Zircon, the
natural stone, can abrade very easily. Emerald, is all too easy to
scratch or even break. Diamonds chip. And there are lots of other
issues and problems with gemstones that get used all the time.
At the same time, metals that we use for jewelry also have their own
problems. Silver tarnishes. They can all become brittle after a time
from metal fatigue. And then there’s the fact that many customers
seem to think that jewelry should be indestructible. How many times
do you hear people say, oh I wear my ring all the time, even
gardening. And how much jewelry repair work do people on this list
do because some piece of jewelry miraculously dare I say
“spontaneously” broke?
Yes, opals can be a bit more delicate than other stones or
materials, but the beauty and mystery of the stuff seems to
supersede that. It just seems like we should simply inform our
customers of that and suggest they be aware that the thing they are
wearing needs some care and a bit of caution. If they want to drop
their ring in a glass of water, to store it, I don’t see how that
can hurt. I doubt it makes much difference but what the heck. But my
gracious, the things people do to themselves, to abuse themselves
and everything around them. How many people overeat and over drink
and are headed for a heart condition? How many people abuse much of
what they own, They drive too fast and get into an accidents. Or
don’t pay attention while they’re driving. Surely it’s not
surprising that they abuse their piece of jewelry. What’s amazing is
they seem to want a guarantee on something as inherently delicate as
thing wire and precious stones and feel like it should last forever.
Let’s face it, maybe they believe what DeBeers likes to say, but
nothing is forever.
Pieces of jewelry are beautiful baubles with which people like to
adorn themselves. They are basically frivolous and unnecessary. We
like them as pretty as we can get them and opals certainly fit into
that category of things. We as makers need to be as informative and
careful as we can, but customers need to be aware that things can
happen and that there is a tradeoff between the beauty and the
potential risk. There it is, though. Between having an opal and some
other stone, I’m going for the opal. Isn’t it really a matter of
reasonable expectations?
Derek Levin
www.gemmaker.com
Where you’ll find lots of opals.
