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Unusual opal

Maybe someone out there can tell me what I saw today… Presented to
me today was an opal, that turned black upon getting wet and,
reverted to normal upon drying. It was real cool. I showed it to a
couple of setters and, a gem dealer who have never seen anything
like it, I give up … Larry

Larry Paul Casting Co. Inc.
740 Sansom St
Philadelphia, PA , 19106

Hi Larry, What you saw might be an odd variety of hydrophane opal.
Hydrophane shows play-of-color only when it absorbs water; and then
it appears to be potch after the water evaporates. It can go through
this cycle (absorbing water, then drying out) an unlimited number of
times without losing stability.

I’ve never seen an opal that turns black when wet!

I hope someone on the list can give you a definitive answer.


It could be HYDROPHANE OPAL .Some Opals in Peru also turn opaque or
milky without water , some people like them and call them Magic Opal
PS: including a photo of Blue Opal

It sounds like a Hydrophane opal. Very pretty but you can’t get it
wet. I had one come over the bench last year. My client had
purchased it from a dealer in Lisbon, Portugal over the Internet.
The dealer was NOT telling the truth about what he was selling. He
was calling it Mexican Fire Opal. She had no way of knowing what she
was getting. It all worked out in the end.

I would like to hear more about this stone too. There is little
out there on Hydrophane.


Larry, The early Gilson synthetic opal turns dark when wetted. They
used to wet them then seal them somehow. Sometime later, the sealer
might wear off and the opal revert back to whitish. Many years ago I
was involved as an “expert witness” in just such a case. Gentleman
had cringed at the prices of fine black genuine opal, after promising
his wife one. He purchased a Gilson synthetic as described above and
presented it to her, forgetting to mention that it was synthetic. At
some point, the stone became loose in its four prong setting
(pendant), and the lady delivered it to a jeweler for tightening (not
the jeweler where it had been purchased). This unknowing jeweler sent
it out to a tradeshop to be worked on,it came back, it was now white,
the owner wound up suing the jeweler who did the reapair work, who
sued the jewelker whooriginally sold the pendant, the pendant was
presented to me for accurate identification by the team of rabid
attorneys out to screw both jewelers. During the initial consultation
with these attorneys, I casually held the stone in a cup of warm
water for a couple minutes and it turned black. You should have
heard the attorneys screaming that I was ruining their case!!! It got
worse, believe me. My guess is early synthetic opal, quite

Wayne Emery