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Judging a round brilliant cut diamond

Miss Sparkly

Brilliant_Rock
Joined
Jan 2, 2010
Messages
1,664
Is there any conclusive way to judge the cut of a RB diamond? I bought one off a secondhand website and it should have a GIA number on the girdle (the original paperwork was lost) which plugged into the HCA gives me a quick answer. In case it doesn't, is there a way to judge the cut using a loupe, microscope and H&A viewer (NOT and idealscope).

Thanks!
 

Luckycharms

Rough_Rock
Joined
Feb 10, 2011
Messages
42
A H&A viewer will give you an idea of the symmetry. I suppose if you are seeing very well formed H&As, then the cut should be up to par with what you are looking for.
 

Stone-cold11

Super_Ideal_Rock
Joined
Sep 9, 2008
Messages
14,069
Luckycharms said:
A H&A viewer will give you an idea of the symmetry. I suppose if you are seeing very well formed H&As, then the cut should be up to par with what you are looking for.
Nope, different things. Optical symm does not equal optical performance.

Why not just buy an idealscope for around 25USD if you do not trust your eyes?
 

Miss Sparkly

Brilliant_Rock
Joined
Jan 2, 2010
Messages
1,664
Don't know if an idealscope would make it to me in time. So the beginner scope is good enough?
 

Miss Sparkly

Brilliant_Rock
Joined
Jan 2, 2010
Messages
1,664
Arg! They don't take paypal and I have no debit card to use thanks to the playstation thefts. New card will be one to two weeks :(
 

denverappraiser

Ideal_Rock
Trade
Joined
Jul 21, 2004
Messages
8,790
Sparkly Blonde|1304085989|2907898 said:
Is there any conclusive way to judge the cut of a RB diamond? I bought one off a secondhand website and it should have a GIA number on the girdle (the original paperwork was lost) which plugged into the HCA gives me a quick answer. In case it doesn't, is there a way to judge the cut using a loupe, microscope and H&A viewer (NOT and idealscope).

Thanks!
No. And with all due respect to Garry above, there's not a generally agreed upon and conclusive way to do it WITH an idealscope either. It would be lovely if only there was. The way the labs do it is unmounted with a trained expert or 3 and a Sarin machine (www.sarin.com) but even that isn't conclusive.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,417
denverappraiser|1304117650|2908266 said:
Sparkly Blonde|1304085989|2907898 said:
Is there any conclusive way to judge the cut of a RB diamond? I bought one off a secondhand website and it should have a GIA number on the girdle (the original paperwork was lost) which plugged into the HCA gives me a quick answer. In case it doesn't, is there a way to judge the cut using a loupe, microscope and H&A viewer (NOT and idealscope).

Thanks!
No. And with all due respect to Garry above, there's not a generally agreed upon and conclusive way to do it WITH an idealscope either. It would be lovely if only there was. The way the labs do it is unmounted with a trained expert or 3 and a Sarin machine (www.sarin.com) but even that isn't conclusive.
Agreed Neil, they are all just rejection methods.
And even if you send the same stone to 100 appraiser's there can be different observation's and opinions.
 

Miss Sparkly

Brilliant_Rock
Joined
Jan 2, 2010
Messages
1,664
It should at least help :) I'm not looking for an ideal cut stone either which makes it a bit more difficult. My goal is to minimize the darkening effect that an ideal cut stone can have in certain lighting while still having a beautiful gem
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
20,775
Sparkly Blonde|1304119535|2908288 said:
It should at least help :) I'm not looking for an ideal cut stone either which makes it a bit more difficult. My goal is to minimize the darkening effect that an ideal cut stone can have in certain lighting while still having a beautiful gem

An IS is not going to help you determine that - or, at least, we know that a well-cut stone of the type that "shows well" in an IS will necessarily go dark in some lighting (spotlighting, direct sunlight). If you're looking for a stone that doesn't go dark in those types of lighting I think you'll want a uniformly "leaky" stone (one that lets light escape through the pavilion pretty evenly throughout the stone), which I think is going to be pretty hard to find in a modern RB, and of course that means you're giving up having a well-cut stone in the first place..


Look at Kenny, Karl, and Garry, and MGR's responses in this thread about darkness in sunlight: [URL='https://www.pricescope.com/community/threads/why-does-a-diamond-go-dark-in-direct-sunlight.132751/']https://www.pricescope.com/community/threads/why-does-a-diamond-go-dark-in-direct-sunlight.132751/[/URL]
Then look at Rhino's explanation about halfway down the page to OP's question in this thread: [URL='https://www.pricescope.com/community/threads/why-does-a-diamond-go-dark-in-direct-sunlight.132751/']https://www.pricescope.com/community/threads/why-does-a-diamond-go-dark-in-direct-sunlight.132751/[/URL]
 

Miss Sparkly

Brilliant_Rock
Joined
Jan 2, 2010
Messages
1,664
I've read those before, thank you. I realize that "going dark" is just a perception. The mounting that I'm putting the stone into is the original ering that DH gave me which I plan on wearing on my right hand. It will only fit a round and the head is integrated so the options for it are small. If I had to choose between a well cut stone that "goes dark" or a badly leaky stone that goes dark in funny places where it shouldn't then I would choose the first (hence the thought of the idealscope). The AVR would be wonderful and if this stone doesn't work out then I'll consider one of those. This one was just way too good of a price to walk away from (especially since it will fit my ring). The original owner said it scored well on the HCA but can't find the GIA paperwork for it.
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
20,775
Ah.. then I think I'm not following what exactly you're looking to learn/find - but it sounds like you've got a plan w/ a stone you've got, so good luck! :))
 
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