More about Mexican fire opals


I've been avidly reading these recent posts about opals on Orchid.
Please, if you have the time, can you direct me to any online
sites or books that may help me understand a little bit more about
Mexican fire opals. 

First of all, as you see I’ve redirected this to Orchid. I hope you
don’t mind. I did delete some things that might identify you, just in
case. This forum is for sharing your question may have a
more general interest than you think.

I wish I could have been there (Queretaro). I have less experience
with fire opal than other opal; but I love it. As with other opal
there’s an enormous range of quality. I have a fire opal cab with
play of color; I’ve never seen another like it. That doesn’t exclude
the possibility of there being another. Last year I saw some work by
Patty Bole, who is a wonderful jeweler from Maine, I think. She used
some fire opal in ERs that were so special in their color I had to
ask what the stone was.

I 've also seen and have some Mexican opal in rhyolite that doesn’t
'do ’ it for me. Much, probably all, of the value is in the eye of
the beholder.The “opaque orange with multicolored, flashy flakes” you
mention could be something special.

But, in spite of what frequently pops up on Orchid one has to be
there, to have the stone in question in ones hands to even attempt a
valuation or an ID.

As for specifics get a copy of “Gem Cutting” by John Sinkankas. It
covers all the basics of gems and is the most accurate source that I
know of. I don’t know of any book specifically covering ‘fire opal’.
But you could go to the card catalog of your local library if it has
inter -library loans and check out the on-line catalog, a great
resource … Value is also in the eye of the beholder. It’s auction
value; meaning it’s worth whatever one is willing to pay. There’s a
more standard system for diamonds because there’s a rigorous grading
system and there are a gazillion diamonds sold annually. Makes it
easier to determine value 'cause there are lots of ‘comps’. The
and value of opal is there are so many variables. It’s also the
reason it’s difficult to price.

The biggest stone market in the world is probably Tucson and there
are many fire opal dealers there. It’s an opportunity to see a great
many fire opals and get some idea of prices. It’s the best experience
there is if you can go. Knowledge of gem material is cumulative; the
more you see the more discriminating you become. I took your question
to be specifically about ‘fire opal’ so I haven’t gone beyond that
particular stone.


I've been avidly reading these recent posts about opals on Orchid.
Please, if you have the time, can you direct me to any online sites
or books that may help me understand a little bit more about
Mexican fire opals. 

I don’t wish to bore anyone but first let’s discuss the definition
of “Fire Opal.” Fire Opal is red, orange or yellow opal, generally
without play of color. It was so named because its body color
reminded people of flames.

Opal with play of color should be called Precious Opal although for
years it has popularly been called fire opal. Very confusing. Orange
opals from Mexico with play of color are sometimes called Precious
Orange Crystal Opal so the terminology is difficult. I own a pair
that are mind-bogglingly bright and colorful. Fire opals (without
play of color) come not only from Mexico, the most famous, but from
places like Nevada, Idaho, Oregon, Brazil, Tanzania, Australia and
probably elsewhere.

If you’re looking for an inexpensive but comprehensive book about
opal buy Fred Ward’s Gem Series volume “Opals.” It has a chapter
devoted entirely to Mexican Fire Opals. If you want a real opal
education pony up the $40 or $50 for the new Lithographie, LLC book
“Opal: the Phenomenal Gemstone.” Excellent! (ISBN 978-0-9790998-0-9)

Mexican precious opal with play of color that’s cut as part of its
native buff or orangy rhyolite matrix is known as “Cantera Opal.”
Cantera means “quarry,” and such stones come from quarries at
Magdalena, Queretaro and possibly other Mexican locations. Removing
such opals from their matrix can easily break them so they are cut
together as one stone.

BewaRe: I noticed a lot of phony Canteras with man-made opal for
sale to tourists on a cruise to the Mexican Riviera a few years ago.
Some natural Cantera opals can be very beautiful: I own a natural
black Cantera opal I wouldn’t part with (well, make me an offer I
can’t refuse). Many colored gems (not just opals) sold at high-volume
tourist locations in Mexico are synthetics or simulants. I noticed
lots of synthetic amethyst and “reconstituted” lapis, turquoise,
malachite/chrysocolla, etc. for sale.

Buyers should be aware that a new synthetic fire opal marketed as
“MexiFire” is currently being sold, as is a synthetic Peruvian blue
opal called “PeruBlu.” I’m not sure why anyone would bother since
natural stones are fairly abundant and reasonably priced but a Thai
company has. Details heRe:

Rick Martin