Green Amethyst, or Prasiolite, heated or unheated?

[boblalux]

I have just purchased via EBay a 33ct green amethyst, claiming to be unheated and from Bolivia. How can I identify this as a natural unheated minerals? I can analyse absorption spectra (hand-held diffraction).
SG is 2.65 and RI is 1.54-1.55

 

[T L]

Date: 6/20/2010 3:26:58 PM
Author:boblalux
I have just purchased via EBay a 33ct green amethyst, claiming to be unheated and from Bolivia. How can I identify this as a natural unheated minerals? I can analyse absorption spectra (hand-held diffraction).

SG is 2.65 and RI is 1.54-1.55

I have never seen green quartz with such saturtion. Odds are it''s a synthetic or coated quartz.

 

[digitaldevo]

Yep, it is more then likely synthetic hydrothermal quartz, coated quartz, Jeweler''s Silica(man-made silica glass) or what is being called Quartz Glass(A fused quartz man-made material). There is quite a bit of this fused quartz and silica glass material being sold as natural quartz because it is extremely cheap at a mere penny or two per carat for the rough. SG and RI can be right in the range on both for natural quartz as well, but a bit softer typically. It is hard to say which it is from a pic because all three types look just about the same unless it happens to be the higher RI silica glass.

A microscope will be your best tool here for starters. A Chelsea filter can help if it is coated. Quartz won''t show any differently in absorption spectra. Never tested the silica glass or fused quartz. I do have some of both here I can run them through my Ocean Optics spectrophotometer if you need/want me to? There may be some deviation or telltale signs, not sure.

 

[Barrett]

hehhe..unheated and from bolivia..lol

 

[chrono]

I highly doubt it is a natural unheated green amethyst for too many reasons: the saturation is too unrealistic and I’ve seen too many of these “Bolivian” material. The SG and RI will not prove anything in this particular case.

 

[RockHugger]

I would say it''s hydrothermal quartz. Natural green amethyst is more of a sea foam green, not a deep green.


Deff. A synthetic!

 

[gsellis]

''Technically'', I guess you could say Prasiolite is ''unheated'' in most cases. Most of it is irradiated. But the irradiated (and heated) is really a light seafoam green (starts as amethyst). That is not. It really does scream man-made quartz all the way. And for a piece that large, vivid, and clean, not natural is the vote.