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Stone ID


#1

Greetings, fellow metalsmiths! Just returned from a 400 mile drive to
Minneapolis to do a nice little show there (Fiber/Metal), and the
color up there along highway 94 could make you cry.Meanwhile, I have
a question I hope someone will feel like answering. A student of mine
brought a stone to class that was sold to her as “Andean opal”. Now,
I’m no stone authority, but I never heard of Andean opal, and the
stone looked to me like a blue moonstone–very pretty, maybe 3
carats, pale blue oval cab, slightly cloudy, typical moonstone
irridescence. She paid $15 a carat. So, what do you think it is? Was
she ripped off? Is there such a thing as Andean opal? If it is a blue
moonstone, is it worth that price? It is, as I said, quite pretty.
I’m also wondering whether it will be ok in a ring.Thanks, to all of
you for all the wonderful give and take! --Noelp.s.–Judith K.-if
you’re reading, drop me an email!


#2

Noel, I bought some of the exact stone at the Denver show and it was
called Peruvian opal.I bought it because I thought it would look good
in some designs I thought of while looking at it.It is harder than
opal.I paid way less than that but was buying wholesale.I think it has
great color.J Morley Coyote Ridge Studio Where the temp is dropping quick.


#3

Hi Noel, I do sell blue opal which sounds like what you have
described. My suppliers have referred to it as Andean opal or
Peruvian blue opal. It is a very pretty stone. Diane

coming soon: http://www.sweetgemstones.com
still closing http://www.jdfindings.com


#4

there is opal from the andies… some is blue, some is green. it is a
massive opal and very little is transparent. it could very easily look
like moonstone. check it’s sg and look at under a microscope. that
should tell you the answer…

rocky


#5

Hello, Yes, there is such a thing as Andean (Peruvian) Opal. There’s
a pink and a blue variety. High quality blue cabs that are fracture
free can display a lovely shimmer and warrant $15 a carat. I cut one
once that had almost a cats eye effect and was so bright it appeared
to glow. This is an example of both pink and blue set in jewelry
displayed on the rough stone it was cut from:
http://lapidaryart.com/gallery_images/img3013.html The blue is quite
heat sensitive in my experience although I have used it in rings
without a problem. It is opal so the same care in setting needs to be
taken as with other opals. Make sure polishing is done before setting;
even this amount of heat can cause fractures to grow, and avoid the
ultrasonic. The pink is not so sensitive.

Enjoy!

Amy O’Connell
Amy O’Connell Jewelry
http://LapidaryArt.com


#6

Noel - Blue Andean (actually Peruvian) opal has become quite popular
in the past 4 or 5 years. I first bought some in the very late 80s
and found it interesting to cut. In is somewhat less heat-sensitive
than precious opal, but is still definitely subject to heat. As to
the price per carat for the stone, I couldn’t say if it is fair - a
lot has to do with the finished quality of the stone, primarily
translucency vs. transparency, and depth of color.

Jim Small
Small Wonders


#7

Noelp, Yes, there is such a thing as Andean Opal. It is a common opal
which ranges from blue/purple color to nice bright blue in the
lapidary grades. Common opal is opal without fire. Prices on this
opal can vary according to the quality of the stone and the quality
of the cutting. Therefore, without appraising the stone, an off the
top of your head dollar figure is not appropriate. Opal can be
readily distinguished from moonstone by gemological testing.
Appearance is the most inaccurate identification. Have the stone
positively identified before performing jewelry work. You may want
to mount the stone differently if you know that it is an opal and not
a feldspar.

Gerry Galarneau


#8

Hi there, Diane you are right, the stone Noel was talking about is
called Andean Opal, it is very popular and easy to find here in Peru.
Carmen :slight_smile:


#9

Noel,

I bought some Andean opal about five years ago. The stone were cut
across the matrix so I had beautiful wide bands of shimmering blue
with smaller bands of browns.

Wonderful material to set. I hope you enjoy working with it.

L.J. Smole
White Fox Workshop
Ozark Mountains, USA


#10

Just a word of observation about this Andean opal --. First, it is
truly beautiful. Second it does have a tendency to crack, rather like
some of the precious opal – i. e. it looks fine initially, and then
one day you come back and find a crack in it. (If they mine it with
dynamite, it’s probably the stresses working their way out --) I bought
several cabs of it. Lovely. But in the time since I bought them (about
a year), a couple have developed cracks. while just sitting there.
Third – it’s fragile! If you drop it, it will probably break.
Margaret


#11

Noel, Indeed, there is a stone such as you describe. Although I have
never seen any with moonstone type alduresence. I believe it is from
Peru (also available in pink) so the name “Andean” is not far
fetched. If , indeed , the stone shows moonstone phenomenon, it may
be worth the $15.00/ct. That would be a rare stone. The material
usually found is $.20 to $1.50 a gram in the rough. My own material I
sell at about $2.00-$3.00/ ct. for finished goods. But I would not
bother with a 3ct. stone unless it was really good material. Feel
free to contact me if you need any more info. later, Mark Thomas Ruby
SunSpirit Designs


#12

Noel, Judging from what you said Noel, I think it is moonstone. The
iridescent quality and its cloudy nature are typical of moonstone. Is
the iridescence a blue shade? As for the price, I can just tell you it
depends on the quality of the stone but I myself haven’t seen it up at
$15 a carat; however, I only wholesale to the trade. We sell moonstone
anywhere from $1.00 a carat to around $8ish. Hope that helps…ohh
one other thing, I myself have never heard of “Andean Opal” and its
probably a name due to either the locality or just a name attached to
it because of its characteristics.

Intimate Gems
Farooq


#13

Noel, I bought some of the Peruvian Blue “opal” several years ago
and saw some of it in a local Lima market place in '93 when I visited
Peru. It is also advertised in the Lap Journal I believe. The “Andean
opal” I have is pinkish rather than blue and I have seen it selling as
large flat chunks at some shows. Both stones cut very nicely and take
good polish. I figure they are 6 to 7 hardness. Not sure what
these stones really are though they may be massive non-gem opal (no
play of color). Can any one out there give more specific

Cheers from Don at The Charles Belle Studio where simple elegance IS
fine jewelry!