Amethyst or glass?

[glitterata]

Is there an easy way to tell an amethyst from glass? I bought a sweet little pin at a flea market and I''m wondering what the "stone" is. I think it''s probably glass--the lady sold it to me as glass--but is there a way to tell for sure?

It''s a sterling pin about an inch long and a quarter inch wide, set with a long, rectangular, transparent, light-purple stone, with three marcasites on each side. It looks to me like it''s from the 30s or so. It''s marked 925 and it cost me fifteen bucks. I don''t really care what it is--glass is fine with me--I''m just curious.

 

[innerkitten]

I don't know anything about amethyst identification but it sounds nice. Do you have a picture.

 

[Michael_E]

glitterata,
Glass in inexpensive pieces usually is molded and not cut. This will show up, especially on the pavilion "facets" as dimples in the center of the facet surface and very rounded facet edges. Glass also shows distinct swirl lines and elongated shiny bubbles. These things can be definitive if they are visible and distinct.

 

[mogok]

Hello,
Amthyst is dichroic and Double refractive uniaxial (DRU) as quartz belongs to the trigonal crystal system and glass is amorphous.
It means that using a polariscope or a dichrsocope (if the stone has color) or even a microscope you can make the difference.
With the polariscope glass will show SR (Single refractive reaction), amethyst no.
With the dichroscope Amethyst will show a very weak dichroism glas no
With the microscope amethyst will show some doubling of facet jonctions, glass no.

Now with a microscope as Micheal has said there are several otehr feathures than can be checked in order to differentiate the 2 stones.

All the best,

 

[glitterata]

Thanks, all!

I examined the stone with a loupe, but it was inconclusive. The facets looked fairly sharp, I think--not as sharp as a diamond, but sort of sharper than my tsavorite, I think. I saw a few little chips and one biggish chip that's hidden under the edge of the setting. No surface wrinkles; a few little scratches; no obvious bubbles, but something that could have been a streak of tiny bubbles but could also have been a fingerprint or dirt on the surface.

I left home this evening wearing the brooch & planning to photograph it tomorrow when the sun comes out. I met my best friend for dinner. She said, "What is that pin? That's so pretty," and in an impulse of affection I pinned it on her blouse and said, "It's yours." So no photo, but if you see a beautiful woman with big brown eyes and silver hair wearing a pale purple pin set in silver with marcasites, her name is Maggie and she's the most wonderful person. And if you happen to have a dichroscope with you, you can solve the glass-or-amethyst mystery, too.

 

[chrono]

Glitterata, your story of friendship really touched me. That was a very sweet gesture.