Can these be Iolites or just Glass

[Alex_Paul]

I got 2 stones, both of them have density of 2.57 , or very close to it. Can they be Iolites , or it is just a glass ?
The pear-shaped one has some inclusions , that look like round and needle-like bubbles.
Thanks in advance,
Alex

 

[Nosean]

Separation of Iolith and Glass is extremely easy.

Glass has only one color in all directions and Iolith is a gem with a strong pleochroism - 3 different colors.

So rotate the stone...

Think it is glass... or synthetic spinel if your density is not correct....

Test it with your lips - compared to a gem like Quarze Glass feels faster warmer than the gem after a few seconds.

 

[stracci2000]

This does not look like iolite to me, both look like glass. The bubbles are a dead giveaway.
Iolite is more violet than blue in color, looks grayish-brown when viewed from certain angles.
if you see no brownish color shift, then probably not iolite.
Also, these pieces look watery, which is usually a sign of glass.

 

[Alex_Paul]

Thank you. Both stones for some reason don't get warmer when I tested with the lips, the temperature feels the same for more than 10 sec - lower than lips, if I am correct.
Also when I looked through pear-shaped stone at the sun - there is very bright purple color along the border (very different from other parts). Rectangular has only different blue colors when I rotate it - light and dark blue (they look like different blue colors). Interesting if there are synthetic Iolites emulating some properties of natural ones.

 

[Tourmaline]

Glass.

 

[minousbijoux]

I'm curious why you think they may be iolite?

 

[Bron357]

Synthetic Sapphire, pretty, fairly durable but man made and very cheap.

 

[pwsg07]

The pear looks like tanzanite

 

[pwsg07]

Is 2.57 the density or the SG?

 

[Alex_Paul]

Is 2.57 the density or the SG?

Sorry , it is specific gravity.

 

[Nosean]

Density IS SG!!

 

[Alex_Paul]

Density IS SG!!

To be honest, since I am newbie in this area, I am measuring it (Density or Specific gravity) using Archimedes principle with high-precision scales (1/1000 of grams), so I don't have special tools. But from physics perspective it should work fine.

On one of the website they say that Density of Tanzanite is 2.55 - 2.57 , is it error :

http://www.jewelrycentral.com/Target_Tanzanite.asp

-- I thought it is Iolite because of Density / Specific gravity and the color of the stone.