Colour change Siberian Amethyst

[cinnabar]

Is this for real? Is there such a thing as "genuine colour change Siberian amethyst"?

eBay ring

I''m not familiar with any kind of colour change amethyst, but this sounds and looks to me suspiciously like lab alexandrite.

Maybe the seller is a bad photographer, but I can''t tell any difference in colour between the pics; they just look to have a different filter or have had the hue photoshopped to be pinker all over.

I''m not thinking of bidding on the ring, btw. I just wanted to know if there was such a thing as colour change amethyst.

 

[rainbowtrout]

While there *is* such a thing as a Siberian amethyst (darker and a bit reddish in color I think) I have no idea about color change...I read they can fade though.

 

[Richard M.]

I''ve written the seller to ask about the color-change properties of the stone. I''ve never heard of CC amethyst either. Siberian amethyst is distinguished by its wonderful deep purple color and the presence of red or blue ''flash'' -- sometimes both. But that''s not the same as color-change. It''ll be interesting to hear what the seller has to say -- if there''s a response.

Yes, the images look a lot like synthetic color-change corundum.

Richard M.

 

[Richard M.]

Okay, here''s the seller''s response:

"HEY THERE, YES IT IS AN INTERESTING GEM....WE IMPORT A GREAT MANY GEMS FROM THE EASTERN EUROPEN BLOCK AREA AND THESE BEAUTIES ARE INCREDIBLE. LOOK AT THE PICS.... I USE A REGULAR GE REVEAL LIGHT BULB AND A TUBE TYPE DESK LIGHT"

Note there''s no mention of making a white balance adjustment. I''m not really sure what''s going on with this stone but here''s a guess:

I made this image of a medium-toned Uruguayan amethyst of slightly pinkish-purple hue using incandescent light with white balance set for incandescent.

 

[Richard M.]

Without changing white balance from incandescent I switched the light source to 5500 K. fluorescent (approximately daylight at noon) and got the result below. But just because I''ve never heard of color-change amethyst doesn''t prove there''s no such thing. Maybe someone else will be able to give a better explanation. One thing''s for sure: the amethyst in my images is not a color-changer.

 

[Richard Sherwood]

If there''s such a thing as "color change amethyst" it sure snuck past me.

 

[PrecisionGem]

Almost every stone has some amount of color change to it in different lighting. Tourmalines epecially pink ones usually look much better under florencent or daylight compared to an incadesant bulb. Amethyst will look different under various lighting also. Color change is thrown around way too much on Ebay. I have yet to see any really high end gems sold on ebay for cheap prices. If it looks too good to be true...

 

[psano]

Is it easy for a gemologist to tell if a stone is a Siberian amethyst vs some other purple stone? I have an old antique ring that fits this description. It''s a reddish purple and under certain types of light flashes deep blues/purples and is quite stunning. I''d love to find out if this is what it is.

thanks,

Patti

 

[Richard Sherwood]

Hi Patty. Yes, it would be easy enough for a gemologist to determine if your stone is a natural amethyst with Siberian "type" color. That category of color has a very distinctive look.

However I''m not aware of any gemologist''s performing actual country of origin determinations on amethyst.

 

[psano]

Rich, are any specific tests required to check the stone, or can a gemologist just look at it w/the naked eye and determine that it''s genuine? I was wondering what I should ask about or ask for when taking it to a gemologist... like a written report?

Sorry if these questions seem tedious. I appreciate your help.

 

[dimonbob]

A gemologist cannot just eye-ball an amethyst and tell you if it is natural or synthetic or where it came from.

There are some very good Siberian amethyst out in the marketplace that is synthetic. They cost about the same so most jewelers will never know the difference.

Paying a gemologist to tell the difference might cost you more than the amethyst.

Furthermore not all gemologist have the same knowledge. I once had one of my ex-students that worked in a Beverly Hills jewelry store come to me with a necklace and needed help in identifying it. They were quartz beads. One of the easy gems to identify with a little knowledge.

 

[Richard Sherwood]

Hey Bob, where you been? What are you doing slumming in the colored stone section?

Psano, the gemologist would have to perform a refractive index test to determine if the stone is amethyst, and then a polariscope and microscopic examination to determine if it is natural or synthetic.

I do a couple additional tests, measure the stone, and take a photo for the typical gem ID report. To give you an idea I would probably charge in the $30 neighborhood for a written ID on a nice amethyst of decent size.

 

[dimonbob]

Hi Rich,

I know for you to figure out the amethyst seperation might be easy and not expensive but I know some gemologist that would not have a clue. Finding a good gemologist is like finding a good doctor. There are good ones and some that should be working somewhere else.

Actually my first love is colored stones. When I was at GIA I was a Gem Ident. instructor. The students thought I could sight ID anything but I just memorized all the student stones. I wouldn''t give them the answer to what it was but I would tell them what to look for to find the answer.