GemAppraisers DIY Cut Grader VS HCA

[Creamyitalian]

This is my first post although I have been doing a lot research on these forums and elsewhere. I''ve come across two diamonds and managed to get most of the specs for both.

THE FIRST:
Ct: .91
Measurements: 6.26-6.30x3.81 (seems like it is a good diameter for its weight?)
Color: H (no flouresence)
Clarity: SI2
Depth: 60.7
Table: 57
Girdle: thin to medium
Polish: VG
Symm: VG
Crown Angle: 34 deg
Crown Height: 15%
Pavilion Angle: 41.2 deg
Pavilion Depth: 43.5%
PRICE: $3267


THE SECOND:
Ct: 1.06
Measurements: 6.48-6.54x4.06
Color: I (strong blue flouresence to hopefully offset the lower color)
Clarity: SI2
Depth: 62.4
Table: 57
Girdle: thin to slightly thick
Polish: VG
Symm: VG
Crown Angle: 35 deg
Crown Height: 15%
Pavilion Angle: 41.4 deg
Pavilion Depth: 44%
Price: $4006


Well first, what are your impressions of the diamonds?

Secondly, the thing I''m most concerned about, are the different grades given by GemAppraisers.com DIY Cut Grader and the HCA on Pricescope. The first diamond was rated a 1A (on GemAppraisers.com) which is the best you can get. However, when I put it through the HCA, it only got Very Good in the 4 categories and a rating of 2.9 (2.3 if you use % instead of angle).

The second diamond was rated 1B (on GemAppraisers.com), but when it went through the HCA it got VG for Light, Fair for Fire, Fair for Scintillation, and VG for Spread for a rating of 4.9. NOT SO GOOD!!

So, especially for the 2nd diamond, how can the cut be so 1A or 1B but have such bad scores for the HCA? At least the first diamond got Very Goods, although I''d expect maybe some excellents.

Perhaps I don''t understand exactly what the HCA is, but if the Cut is Ideal and 1B, what about it would cause the poor scores on HCA??? I know 62.4 is kinda deep, but not THAT much.

Sorry for the long post, but I''d love some input on this.

Thanks in advance!

 

[Creamyitalian]

Could it be the Pavilion angle causing the bad scores????

 

[JulieN]

yes, the PA angle is giving you low (high?) HCA

 

[oldminer]

Diamond cutters can figure out ways to increase weight and say just inside the parameters on certain stones. The HCA helps weed these out from other things that are parametric based.

We now measure light with a technological device and relegateparameters to a more minor role whenever possible. However, the AGA Cut Class and the HCA have validity within their limitations.