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discrepancy between HCA and GIA tables

JulieN

Super_Ideal_Rock
Premium
Joined
Jul 25, 2005
Messages
13,329
There is a difference of opinion.

I would look for another diamond.
 

BayouKip

Rough_Rock
Joined
May 29, 2011
Messages
13
Right, I guess what I am asking is both plot crown and pavilion angles as a function of table %, in what way are the two opinions so radically different, im trying to get an idea for what it would look like in real life
 

Rockdiamond

Ideal_Rock
Trade
Joined
Jan 7, 2009
Messages
8,400
It's true- there are many differing opinions.
Speaking in general terms: I look at each diamond holistically.
What I mean is, if I'm looking at a 1.00 D/VS1, I might agree with the type of stone the HCA would prefer.
If it's a 5.65ct M/VS1, it would very likely be , for me at least, a different type of stone I'd prefer.

Is this a stone you are looking at in person?
 

BayouKip

Rough_Rock
Joined
May 29, 2011
Messages
13
Unfortunately not, I'm looking at a lot of different stones online. I'm an amateur. I'm looking for some sort of consensus on with the different models (GIA, AGS, HCA).
 

slg47

Ideal_Rock
Joined
Apr 4, 2010
Messages
9,667
GIA, AGS, and HCA use different parameters for cut. In general I think you are safest with AGS ideal (usually don't need HCA here) or GIA Ex with HCA < 2. Pictures and idealscope images can also help you evaluate cut.
 

Rockdiamond

Ideal_Rock
Trade
Joined
Jan 7, 2009
Messages
8,400
BayouKip said:
Unfortunately not, I'm looking at a lot of different stones online. I'm an amateur. I'm looking for some sort of consensus on with the different models (GIA, AGS, HCA).
There's not going to ever be a consensus on which table and depth/ PA/CA LGF combo is best. GIA's range is wider than AGSL- these are the two accepted cut grades by the trade at large.
It's a range. GIA's range is wider- some could argue that makes AGSL a "better" cut grade.
I look at it holistically. Gotta look at the diamond to know
If you could look at some diamonds in real life- hopefully some with GIA, or AGSL reports, you'd have a much better starting point.
 

JulieN

Super_Ideal_Rock
Premium
Joined
Jul 25, 2005
Messages
13,329
I agree that it's important to consider many factors. As for myself, I find GIA cut grading to be unusable as a method of comparing stones.
 
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