Why do REAL diamonds display cz characteristic?

[luvmysparklies]

I''d like to get some expert/knowledgeable consumer opinions on this. I have read that one way to tell a cz from a real diamond is if you tilt the stone/ring that there will be a black fan visible. Well, I have seen this same thing in diamonds. My H&A engagement stone from GOG as well as in my ACA. Why does this occur? I know that there will always be some person out there who will see my e-ring and just assume that it is fake just because it is a decent size-2.4. I hate to think that if I go into a reputable jeweler''s shop, just to look around, that upon glancing at my ring and seeing that "black fan" that it''s automatically assumed that the stone is fake. Why do diamonds do that? I thought that because of the material that a cz is, that the way that it handles light, it is inevitable that the black fan shows, but I thought diamonds were different?

 

[valeria101]

No idea what this "black fan" is all about. It does sound as if this has nothing to do with the material, but is an effect of the shape of the cut, as simple as that. I surely hope that most jewelers on the face of the Earth would be able to tell a huge CZ from a huge diamond when they see one

PS: Where did you read about this "identification method"? I am no huge admirer of faceterd gems (cabs are my domain) but a little red garnet at hand shows something like a dark fan-shape shaddow when tilted too: to me it appears to be just a transparent zone aparent when you look through the table straight through one of the larger pavilion facets).

 

[Garry H (Cut Nut)]

This look?
dark in the crown closest to you and the far side of the table?

 

[Garry H (Cut Nut)]

Shine a light or hold something of a bright color where these rays are going and you should see why

 

[Garry H (Cut Nut)]

ditto

 

[Mara]

Not too sure about the dark fan either, never heard of that.




The only thing I heard about CZ's vs real is that you can see through a CZ (e.g. to a newspaper if the ring is laying on its side).




Plus I can tell a CZ from a diamond by it's sparkle somehow...it's definitely different. Even my Signity Star stone, H&A CZ looks different from my diamond. So I don't think you have to worry...

 

[caratgirl]

LOL, yes, I frequently run across articles that mention the 'V' or fan shaped darkness. Apparently the people writing the articles never actually compared a diamond to a CZ. Surprise, they both have that look at an angle, much like the one pictured above, but a bit more pronounced. I haven't seen a diamond (round) yet that doesn't have that appear. Now, mind you, a CZ shows that in a slightly larger area. I have to admit, I can be fooled by CZ's occasionally when they are smaller and very well cut, but a lot of them aren't. Hopefully I am not just looking at badly cut real diamonds, though.

 

[valeria101]

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On 1/18/2004 9:34:42 PM Mara wrote:


Not too sure about the dark fan either, never heard of that.


The only thing I heard about CZ's vs real is that you can see through a CZ (e.g. to a newspaper if the ring is laying on its side).
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Doesn't your diamond allow the same? This see-through test sounds like another journalistic myth to me... Your following note does not and it surely is the reflected spectrum that tells these apart for me in theory and practice. Oh, I really wish gem identification would be as straightforward as these quick-fix customer advice gimmicks advice

 

[Garry H (Cut Nut)]

V the see thru test really works, and you can see a larger fan thru a CZ than a diamond.

My wife and I bath together in our conservatory / bath room very often. When her diamonds are wet the brownish fan shape inside the table really annoys me. Diamonds with smaller tables suffer less from this.

 

[Mara]

Will have to check into this fan thing, now I am really intrigued! No, Val I can't see through my diamond ...straight through that is...the light play off the facets prohibit that.




Garry...bathing with the wife and all you can look at is the fan in her diamonds? Shame!!

 

[Stephan]

Mara !!!
LOL

 

[Garry H (Cut Nut)]

Well Mara sometimes for a man, well er......
Decided not to make that comment

 

[valeria101]

Never stop learning, as they say...
I guess one could see through a shallow cut diamond with large table: my only try of this trick involved a rather dull diamond which may well hae been blessed with both these qualities. Maybe next time. Thanks for making that V thing for me: that's new on my fun fact list. If the size rather than existance of that dark zone is the catch of the test, than I guess I have some practice ahead

 

[luvmysparklies]

OK, thanks for the replies guys! This puts my mind at ease. I read about that black fan stuff in a Renee Newman book. I think its called "Diamonds" or it's got diamonds prominently in the title, anyway it is a light blue book and it's got pics of engagement rings on the front of it. Your (plural) explanations made sense. Thanks Gary, for that picture example, it was helpful.

The other things are true about cz-you can read newsprint right through it, but you cannot through a diamond. You can also see prongs through a cz and its even worse when the prongs are yellow gold. Anyway, thanks again for the info and reassurance!
Luv