Help with a stone please...

[Puppy Girl]

Hello everyone...!

I am so excited to have discovered this site, and to have happened upon so many well informed people who reside within it. This is my first post, and whilst I have read and agreed to the site rules, I''m not quite polished on the community''s requirements of posting; please excuse my ignorance if I make any mistakes.

I recently got a stone that is dark paraiba blue in overall appearance, with dark blue, and green. Under my dichroscope I see purple, blue and green. Now, I''m a novice user of gem identification tools, so I couldn''t even begin to use my spectroscope because it appears not to work. The stone was supposed to be a tanzanite, and unless this stone is natural/unheated I don''t believe I got what I paid for.

My question for viewers is whether or not anyone knows what type of stone could be all of those magnificent colors. I have attempted to upload a few pictures of my gem, but I seriously doubt that anything could capture the strange beauty of the stone that I have respectfully submitted. Any information would be most gratefully appreciated!

TIA...!

Puppy Girl

 

[Lady_Disdain]

Welcome to PS!

My guess: coated topaz, aka mystic topaz. Please post the pictures, I''m sure that they will be helpful.

 

[Pandora II]

In what sense does your spectroscope not work?

Heated tanzanite may not show any bands at all or very weak ones, which is why you may think it's not working. Untreated tanzanite will show weak bands in the yellow-orange, red, green and blue.

A few other questions on the stone:

- Do you see doubling of the back facets when you look through the table?)

- if you own a chelsea filter, what colour are you seeing there? Tanzanite will show a golden brown colour.

I am presuming that you don't have a refractometer.

Unheated tanzanite is trichroic - shows three colours in the dichroscope - violet, blue and then either green, yellow, or sometimes brown. The violet shade is sometimes quite a reddish violet.

Heated tanzanite will normally look dichroic and only show two colours - violet and blue - BUT, I have read that sometimes the greenish colour will remain even after heating (the brown colour never survives heating).

Heated tanzi will only show violet/blue, unheated will show strong violet, greenish yellow and blue or violet-red, deep blue and yellow-green. So you could have an unheated stone.

If you can see doubling of the back facets it is unlikely to be tanzanite (it's doubly refractive but the birefringence isn't enough to show the double facets) and I would guess it's synthetic forsterite - which gives similar results with the dichroscope to those of tanzanite.

The easiest test is either:

- Combination of Dichroscope and Chelsea Filter - The forsterite will be inert under the chelsea filter whereas the tanzanite will show golden brown.

- Hanneman tanzanite filter or a chelsea filter combined with a Hanneman aquamarine filter - tanzanite will be orange/pink while the forsterite will look green.

Hope this helps...

My guess is that you do have a tanzanite.

 

[Proteus]

I agree that unheated tanzanite is a possibility for your stone.

I once cut an unheated tanzanite which, though trichroic with blue, violet and greenish-yellow hues, had strong enough blue/violet directions to face up a nice, deep blue once faceted. It still showed the greenish-yellow color in certain directions, but faced up more or less like any other tanzanite. It could be possible that you have a stone such as this.

If you have access to a refractometer, that would certainly aid in identifying it.