Bought a sapphire and seems like I received a tanzanite?

[beaujolais]

Can a sapphire really, really look like a tanzanite? I bought a sapphire from Multicolor recently. It was described as light bluish purple on their site. Received it, it''s beautiful but it absolutely looks like a tanzanite. I just had it set and the jeweler said he believes it''s tanzanite.

I wish I could post a photo but my camera does not have macro.

What might be the visual differences between sapphire and tanzanite?

Also wondering, how does a gemologist tell for sure what a stone is? Diamonds have diamond testers but I don''t think there are tanzanite testers.

Thanks.

Note that I do not mean any negativity towards the vendor. This is a beautiful stone and the price was great.

 

[Harriet]

A gemologist can test its refractive index, among other characteristics.

 

[beaujolais]

Ah, great. There it is.

Thanks.

 

[Pandora II]

Personally I would rather have a ''tanzi-looking'' sapphire than a tanzanite any day. It''s harder and more durable for a start. It''s also one of my favourite shades of sapphire.

It would be pretty easy for a gemmologist to tell:

First of all :

Tanzanite:
Mohs - 6.5 - 7
Specific Gravity - 3.10 - 3.38
Refractive Index - 1.69 - 1.70
Trichroic - through a dichroscope you will see three colours

Sapphire:
Mohs - 9
Specific Gravity - 3.95 - 4.03
Refractive Index - 1.762 - 1.778
Dichroic - through a dichroscope you will see two colours.

Basically, sapphire is harder, denser and has a higher RI than tanzanite. You don''t really want to go scratching your stone. If it''s already set it will be hard to measure the RI or SG, but you can easily use a dichroscope.

With tanzanite, you will see 3 colours (if one is green or yellow it may indicate that it''s not heat-treated), with sapphire there are only two colours.

 

[Catmom]

Date: 4/27/2008 10:06:32 AM
Author: Pandora II
Personally I would rather have a ''tanzi-looking'' sapphire than a tanzanite any day. It''s harder and more durable for a start. It''s also one of my favourite shades of sapphire.

It would be pretty easy for a gemmologist to tell:

First of all :

Tanzanite:
Mohs - 6.5 - 7
Specific Gravity - 3.10 - 3.38
Refractive Index - 1.69 - 1.70
Trichroic - through a dichroscope you will see three colours

Sapphire:
Mohs - 9
Specific Gravity - 3.95 - 4.03
Refractive Index - 1.762 - 1.778
Dichroic - through a dichroscope you will see two colours.

Basically, sapphire is harder, denser and has a higher RI than tanzanite. You don''t really want to go scratching your stone. If it''s already set it will be hard to measure the RI or SG, but you can easily use a dichroscope.

With tanzanite, you will see 3 colours (if one is green or yellow it may indicate that it''s not heat-treated), with sapphire there are only two colours.

Yeah, me too, and I do!! My color change sapphire gets mistaken for a tanzanite ALL THE TIME. Even my own jeweler mistook it for a tanzy. I had my ring in to get a sizing bridge added and my jeweler made a remark that they would have to unmount the stone in order to have the bridge added. I was like, Umm NO, i don''t think so. Why do you think you would have to do this an he said that because tanzanite are so soft they couldn''t work on the ring without unmounting it. After I set him straight he spent the next 20 minutes looking at it under the microscope, etc before he believed me.

I can''t begin to tell you how many times I''ve been told about how much someone loves my tanzanite ring! So yes, just by looking they can be mistaken but they are easily distinguished by a gemologist.

 

[beaujolais]

Thanks all. I wonder if GOG has a dichroscope and can do that for me. I live fairly close to them.

 

[Pandora II]

You can get a cheapy one on ebay for about $30 - make sure it''s a calcite one. There are loads of articles online that will tell you how to use it.

 

[beaujolais]

Oh nice. Why not? I''ll look for one then.

Thanks.

 

[Miscka]

make sure to tell us what you find out! Very interesting.

 

[diamondseeker2006]

I, too, love violet-blue sapphires!!!! I hope that''s what it is!!!!

 

[beaujolais]

Thanks all. I really do love the color and characteristics of this stone.

Pandora - can you recommend a brand of dichroscope?

Thanks.

 

[DiamondExpert]

If the setting will allow access to the stone''s surface, taking an RI would be the best/quickest way to determine identity/separation.

As has been mentioned, tanzanite is quite soft and not the best ring stone if you wear it daily.

 

[marcy]

Yes, sapphires can look like tanzanites and I bet it is very pretty. Can''t wait to see it.

 

[Pandora II]

Date: 4/29/2008 10:14:17 AM
Author: sonomacounty
Thanks all. I really do love the color and characteristics of this stone.

Pandora - can you recommend a brand of dichroscope?

Thanks.

I have a couple - one from Gem-A and one I got from ebay for £12 from a dealer in Singapore, it seems pretty good to me, or at least they don''t give different results.

Someone else might be able to comment on if there is a huge quality difference between brands.