Karen, the Nevada opal has some of the finest color of any opal. It
also has some nasty problems, mainly that it is not very stable. I
have had pieces start to craze and crack within 20 minutes of being
removed from water. I have had pieces that went from water clear
with great fire to a sugar cube look within a similar time frame.
Luckily the last resorted to it’s former life after about 10 minutes
in a glass of water. I also have a nice piece of wood with opal in
it. If I wet it, the opal really stands out. I put it in water
over night, and it was just the opposite of the earlier stone, all
the color disappeared. These stones are called Hydorphane Opal.
Some will show color only when wet, others only when dry. Neither
is a very good choice for jewelry. They can vary in weight by
several percent between dry and wet states. Some, when dry, will
stick to your tongue like natural turquoise.
As to your opal, what was the state of it when you acquired it. Was
it in water, or was it a dry stone? Also what is its history, IE
how long has it been out of the ground, and how has it been stored?
If you got the stone dry, and it has been in that state for at least
a couple years, then you might just have a rare Nevada stone that is
stable. They make great jewelry items. If you are not sure of the
stone, let it dry for a while, knowing that crazing and cracking are
possible at worst, and turning milky white is the next worst thing.
Don’t try to accelerate the drying process. Just normal room
temperature with mid to low humidity, IE 50% to 20%. If the stone
stands this for six or seven months, then you may have a jewelry
As to care after you set it, a little moisture will not harm it, and
might do it some good. The moist tissue in a zip-lock bag is
sometimes called the “Nevada Cure” as it slowly lets the moisture
escape and reduces stress on the stone. The normal cure time is on
the order of two to three years without opening the bag. The results
are spotty though.
If the stone has been dry, and it has been cut and polished for
several months to a year and is still in good shape, the best care
you can give it is to just occasionally wipe it down with a damp
rag. Never store it in a safety deposit box as the extreme low
humidity, on the order of 1 to 2% will damage even a sound
Australian opal. Never use any oils on the stone and Never use
glycerine (an alcohol family chemical that will suck any remaining
moisture out of your opal). Avoid extreme temperatures. Nothing
below freezing, and nothing so warm that you can’t hold it in a
closed hand. This advice applies to all opals.
Don at Campbell Gemstones