Congratulations To Richard M.

[pricescope]

"Bright Gem, Big Question
By Gary Roskin, G.G., FGA, Senior Editor
JCK-Jewelers Circular Keystone -- 11/1/2005
“You’re examining a women’s 14k white gold ring with a beautiful pear-shape,
6.64 ct. stone that’s a slightly grayish, slightly greenish, medium-dark
blue not unlike the color of aquamarine. You have only a loupe."

...........................................................

"“Send your best guess to Gary Roskin, senior editor, and win a free gemstone
image from the JCK Research and Stock Art Store. The first jeweler to
correctly identify the stone will win..."

We hope the Winner of this contest - our own Richard M. will tell us about tips and hints given.


“The right answer, however, was there all along and Rick Martin from
Camarillo, Caif., figured out that it was greenish-blue zoisite..."

 

[belle]

well done richard!
please tell us more about zoisite and the clues that gave you the answer.

 

[Richard M.]

Date: 1/31/2006 8:53:03 AM
Author: belle
well done richard!

please tell us more about zoisite and the clues that gave you the answer.

Thanks for mentioning this and your kind words. The quiz was a lot of fun, and it was more fun to get it right!

If I''d been able to see the stone ''for real'' the process would have been easier because the fact the stone lacked zircon''s very high R.I. would have been apparent at a glance. Using Visual Optics I could have done a quick bare eyeball estimate of R.I. However, from the photo and information given (facet rounding, double refraction) blue zircon appeared to be the best fit and that''s what most people guessed.

But the color just didn''t seem right for zircon and that set off alarm bells. Tanzanite is a variety of the mineral zoisite and the color wasn''t right for Tanzanite either. But I''d seen other zoisite colors so I mentioned the mineral as a possibility -- especially if the stone exhibited trichroism, which couldn''t be established from the photo. Zoisite crystallizes in the orthorhombic system, a structure that allows light three different paths through the stone (and three different emergent colors at separate angles).The presence of trichroism combined with other properties would be a strong indication of zoisite.

Long story short, that was the right clue. Gary Roskin, the gemology editor, emailed that the stone shows trichroism but it''s very weak, probably the result of heating. I suspect the stone was found with Tanzanite but has an offbeat chemistry that sets its color apart. Still it''s a very pretty gem and certainly a conversation piece!

Richard M.

 

[strmrdr]

Way kewl :}
Congrates!!

Thank you for all your help here on the forum.

 

[Richard M.]

Thanks Strm. Happy to help when/if I can.

Richard M.

 

[belle]

awesome. thanks for taking the time to share your knowledge with us richard, it is greatly appreciated.

 

[Kaleigh]

Congratulations Richard!!!

 

[MINE!!]

A HUGE CONGRATULATIONS OUTGOING!!!!!

 

[kaylagee]

Neat!

 

[Richard M.]

Thanks everone. Irina asked me to explain this in more detail.

Gary Roskin G.G., F.G.A is the gemology editor of JCK (Jewelers Circular-Keystone), probably the oldest jewelry industry trade magazine in the U.S. He writes a monthly feature called Upfront/Gems in which various timely gem topics are discussed.

Last November he published a little quiz concerning a puzzling blue pear-shaped stone set in a diamond halo that was encountered by a Los Angeles diamond dealer. All the dealer had was a loupe and his gem knowledge to do the I.D. Roskin challenged his readers to see what they could do with the information he published.

The 6.64 ct. stone (pictured in color) was an unusual hue. Roskin described it as: "slightly grayish, slightly greenish, medium-dark blue not unlike the color of aquamarine." It struck me as being dark and not quite right for aqua.

He also determined the stone had rounded facet junctions and was double-refractive. The latter ruled out spinel, and the rounded facet junctions indicated a fairly soft stone. He ruled out aqua and maxixe beryl on that basis.

I decided to give the quiz a try, figuring there would be many correct answers from the magazine''s large readership of gem industry professionals. Other entrants guessed blue zircon (most), kyanite, topaz, benitoite, synthetic forsterite, apatite, dyed quartz, synthetic blue quartz, taaffeite and an aqua/glass doublet.

Apparently my entry was the only one to single out blue nonvarietal zoisite.

Richard M.

 

[Kaleigh]

Well even bigger congrats to you, that's great!!!

Having never seen one, can you post a pic so we know what one looks like???

 

[Garry H (Cut Nut)]

Well done Richard, congrats

We appreciate your advice here on the forum - you really know your stuff

Here is some rough zoisite

You might prefer the more familiar name Tanzanite for the purplish blue variety?

 

[Kaleigh]

I just got my JCK magazine today. I saw the article, and got to see the beautiful stone. Well done!!!! It's on page 56 for those that subscribe.

 

[flopkins]

oooh congrats!!!

 

[researcher]

That is so fantastic! Congrats!!!

 

[Richard Sherwood]

Now we can all say we knew you "back when"...

 

[Richard M.]

Date: 2/1/2006 8:34:51 AM
Author: Richard Sherwood
Now we can all say we knew you ''back when''...

Richard, you know I''ll always send the tough ones to you! My object is to know enough to realize when it''s time to find a real expert.

Thanks for your comments everyone.

 

[Hest88]

Congratulations!!! So, what stone did you win?

 

[belle]

Date: 2/1/2006 11:24:48 AM
Author: Richard M.


My object is to know enough to realize when it''s time to find a real expert.

that, in my opinion, makes one far more wise.

congrats again, and thanks for sharing your knowledge.

 

[valeria101]

Glad to read this!

Maybe we should have some quiz like that around here - after all, every gem picture online is one

 

[Richard M.]

Date: 2/1/2006 12:33:52 PM
Author: Hest88
Congratulations!!! So, what stone did you win?

I didn''t win any stone -- it was just for fun. But if I can ever get untangled from daily commitments and head to Tucson as I was scheduled to do a couple of days ago, Roskin has asked me to be his dinner guest as a ''prize.'' Meeting and chatting with him will be enough for me, if I can make it.

Richard M.

 

[Hest88]

Date: 2/1/2006 4:32:23 PM
Author: Richard M.

Date: 2/1/2006 12:33:52 PM
Author: Hest88
Congratulations!!! So, what stone did you win?

I didn''t win any stone -- it was just for fun.

Oh duh. I read "gemstone image" as "gemstone" and got even more excited for you!

 

[Richard Sherwood]

Date: 2/1/2006 11:24:48 AM
Author: Richard M.

Date: 2/1/2006 8:34:51 AM

Author: Richard Sherwood

Now we can all say we knew you 'back when'...

Richard, you know I'll always send the tough ones to you! My object is to know enough to realize when it's time to find a real expert.

Thanks for that nice comment Richard, and I'll send you the 20 bucks as agreed...

 

[Richard M.]

Date: 2/1/2006 7:37:40 PM
Author: Richard Sherwood

Thanks for that nice comment Richard, and I''ll send you the 20 bucks as agreed...
[/quote]

Only Twenty? You must have been negotiating at Keystone!

Richard M.

 

[valeria101]

Quick question... what ruled sillimanite out?

 

[Richard M.]

Date: 2/1/2006 11:57:13 PM
Author: valeria101
Quick question... what ruled sillimanite out?

Size, color and rarity. Assuming the typical 70% weight loss in cutting from rough, a 6.45 ct. finished stone would have required a 22+ ct. gem-grade rough -- enormous for sillimanite. That, combined with the rarity of facet-grade sillimanite, especially in medium-dark blue, quickly ruled it out in my mind. Also, its greater hardness would make it less likely to have rounding of facet junctions. Still, sillimanite would have been a logical guess based on properties alone.