The problem had been caused because the owner wore it all the
time, doing gardening, washing dishes, swimming etc. and the
surface had absorbed a great deal of water with dissolved salts.
The water had evaporated from the stone leaving the salts behind -
rather like a kettle furring up.
There is a type of opal called hydrophane that can absorb quite a
bit of water. But it works in reverse of that scenario: it loses its
play of color when it dehydrates and flashes back to life when water
is restored. It’s mainly a curiosity and not a type of opal used
commercially as a gem. The idea of a fine black opal losing its
brilliant play of color for the reasons suggested is nearly
impossible in my opinion. Black opal from Australia is one of the
most stable and least hygroscopic (thirsty) of all opals.
I’ve only been cutting, setting and selling opals for a bit over 40
years, so I probably have quite a bit yet to learn. Still, in all
those years I have not once seen gem-quality opal damaged or
discolored in any way by water or water-borne agents, including
grease or oil, although I keep reading that it happens. I’m not
saying it isn’t possible but you’d think I’d have run into just one
example in that time.
What I have seen, repeatedly, are opals in rings that have been
scratched to the point that their play of color is nearly invisible.
Simple repolishing restores them to their original splendor. Opal is
roughly the same hardness as glass. It is scratched by ordinary dust
made up of minerals like silica. An opal worn while digging in garden
dirt or washing dishes is certain to to be scratched and lose its
polish over time.
The owner of that valuable opal is lucky to have avoided the
disaster suffered by a 1+ carat diamond I took in for a repair job
recently. The owner, also an avid gardener who never removed her
ring, had managed to break a large chunk off the pavilion just below
the girdle. The fine F-color stone was beyond recutting to anything
close to its original size.
Some of the comments about opal I’ve read here the past week or so
have left me pounding on walls and howling at the moon! Any jeweler
who has the chutzpah to sell tanzanite should never, under any
circumstances, complain about the “fragility” of opal! Opal, like
far softer gems including pearls, requires reasonable care in the
wearing and handling.
It is the job of the jeweler to make certain customers are fully and
factually informed about their purchases. To do that, they must
first inform themselves and not endlessly repeat myths as fact. They
should start by studying a few basic books like Fred Ward’s excellent
"Opals," now out in an updated edition. His chapter on “Buying and
Caring for Opal” is a must-read. There are several other very fine
modern books about opal, and I look forward to seeing Orchid
contributor Richard Wise’s new opal book when it is published. He
has written with expertise and authority on many gem subjects.