Sparkle factor blue zircon vs blue spinel

[SapphireLover]

Out of blue zircon or blue spinel, which one sparkles the most? Do either of them give off fire?

 

[MakingTheGrade]

I think zircons have more "sparkle", both give off dispersion though.

For me, it''s really a matter of what shade of blue you like, zircon blue tends to be a lighter blue-green/carribean blue, whereas spinels tend to be a darker blue-grey.

 

[SapphireLover]

Thank you!

I absolutely LOVE your pad in the lotus setting. It makes me drool.

 

[coatimundi_org]

The zircon will have a much higher dispersion (fire) .038 compared to spinel's .020. Diamond's dispersion is .044 for reference.

Zircon will have softer appearing facet junctions than spinel--which will have a sharper appearance.

Blue spinel is often desaturated which can affect the overall look of the stone, but spinel is much more durable than zircon. A good cut helps.

Zircons are heated to achieve that blue color--but this is common, as almost all blue zircons have been heat treated.

A well cut zircon will ultimately have more fire and brilliance than a blue spinel. I have seen fine blue spinel that is amazing, but it is extremely rare and of course, top $$.

 

[T L]

Zircons are also doubly refractive, and when they''re not cut well, this often gives them a sleepy apperance IMO.

 

[coatimundi_org]

That's the doubling of facet junctions as a result of a very high birefringence. (high type zircon) Well cut zircon can also display doubling.

 

[T L]

Date: 5/25/2009 12:04:53 PM
Author: coatimundi
That''s the doubling of facet junctions as a result of a very high birefringence. (high type zircon) Well cut zircon can also display doubling.

Coati,
What is "high type zircon?" Thanks for the explanation. I just know that I''m not a fan on the doubling of facet junctions that is sometimes displayed in certain zircons. It gives me a headache to look at that.

 

[coatimundi_org]

TL,

Zircons display an interesting range of properties. They are generally classified in three types--high, medium, and low.

Low property zircon--damaged crystal structure as a result of radioactive elements. They have a lower RI, SG, and birefringence. They may appear singly refractive. Some low property zircons are close to amorphous.

Mid property zircon--Some radioactive damage to crystal structure. Their properties sit in between low and high. So lower, RI, SG, and birefringence than high property.

High property zircon--Undamaged crystal structures--for the most part. They have the properties that zircons are known for--high birefringence, RI, etc.

We mainly see high property zircon in faceted stones.

Zircon is brittle, so the facet junctions abrade quickly. Any doubling of smooth facet junctions appears so much worse when they are abraded. The color of heated zircon can be so pretty, but it''s a rather fragile stone.

 

[ma re]

Ditto to things Coati and TL said. I don''t own either of those, but in theory, spinel should have a sharper, more distinct sparkle, but zircon is likely to be more scintillating, i.e. give an impression of "more life". If by sparkle you''re referring to light return (a bling), the tone of color (lightness or darkness) also plays a role there, cause the lighter the stone, the sparklier it''s likely to be - as there''s less light absorbed, so more can be reflected.

 

[T L]

Date: 5/25/2009 12:27:56 PM
Author: coatimundi
TL,

Zircons display an interesting range of properties. They are generally classified in three types--high, medium, and low.

Low property zircon--damaged crystal structure as a result of radioactive elements. They have a lower RI, SG, and birefringence. They may appear singly refractive. Some low property zircons are close to amorphous.

Mid property zircon--Some radioactive damage to crystal structure. Their properties sit in between low and high. So lower, RI, SG, and birefringence than high property.

High property zircon--Undamaged crystal structures--for the most part. They have the properties that zircons are known for--high birefringence, RI, etc.

We mainly see high property zircon in faceted stones.

Zircon is brittle, so the facet junctions abrade quickly. Any doubling of smooth facet junctions appears so much worse when they are abraded. The color of heated zircon can be so pretty, but it''s a rather fragile stone.

Thanks for the information on zircons. How fascinating!! Are High property zircons more attractive than low and mid property ones? Is that why they are seen more in faceted material? I guess that''s something else to be on the lookout for when shopping for zircons.

 

[SapphireLover]

Thanks for the helpful replies. I think I am leaning more towards blue zircon. Scintillating is definitely the type of sparkle that I love.

 

[coatimundi_org]

Date: 5/25/2009 12:32:13 PM
Author: tourmaline_lover

Thanks for the information on zircons. How fascinating!! Are High property zircons more attractive than low and mid property ones? Is that why they are seen more in faceted material? I guess that's something else to be on the lookout for when shopping for zircons.

You're welcome, TL.

There are (low type) "metamict" zircons which are generally green. Metamict means that the crystal stucture is partially broken down by radioactive elements. Sometimes, low type zircons have cool iridescent looking inclusions as a result of the damaged crystal structure, or they might display interesting fire as a result of light interference, but that's pretty rare. They are usually a dull olive green.

I'd say high property zircons are far more attractive than low or mid property (most faceted zircons are high property), but it would be cool to find a low property with interesting inclusions or one that displays nice spectral colors.

eta: If you heat a metamict zircon, the crystal damage is "corrected" or reversed, and you end up with a high property zircon. Interesting, eh?

 

[coatimundi_org]

Date: 5/25/2009 12:35:34 PM
Author: SapphireLover
Thanks for the helpful replies. I think I am leaning more towards blue zircon. Scintillating is definitely the type of sparkle that I love.

Please post pics when you get your stone!

 

[T L]

Great info Coati, thanks!

 

[chrono]

One can find more sparkly blue zircons than blue spinels. Also better colour because blue zircons are brighter whereas many blue spinels are dark or have a gray mask.

Coati,
Thanks for the info on the different types of zircons. Very interesting stuff.

 

[Stone Hunter]

Date: 5/25/2009 12:27:56 PM
Author: coatimundi
TL,

Zircon is brittle, so the facet junctions abrade quickly. Any doubling of smooth facet junctions appears so much worse when they are abraded. The color of heated zircon can be so pretty, but it''s a rather fragile stone.

This is why I''ve stayed away from Zircon so far...I don''t think I mix well with fragile stones. Very interesting information. TFS