Confused about the Holloway Cut Advisor

[Korenne]

I need your help in understanding how the Holloway cut advisor works.

Let's start with a diamond.

Color: G

Cut: Excellant

Carat: .72

Polish: EX

Symmatry: EX

Depth: 68.2

Table: 58

Crown Angle: 36.0

Pavillion Angle: 41.2



So this is a diamond with an Ideal Cut, ex symmatry, ex polish etc. But when I type these stats into the Holloway Cut Advisor... it looks incredible poor. It rates it at a 5.5.

Light Return: Good

Fire: Fair

Scintillation: Good

Spread: Very Good.

I thought the purpose of labeling a cut as Ideal or Excellant was that it would have better than "good" light return, fire. etc etc. Why is this diamond labeled as Ideal? Am I just totally confused about the Holloway Cut Advisor? Honestly the HCA has given me better results with some of the "very good" cut diamonds.

Diamond Experts. Help me understand!

 

[JulieN]

WHO labelled it ideal or excellent? that is out of bounds for AGS and GIA. A 68 depth is unsalable, I rarely see anything more than 65.

 

[hawk25]

It's no wonder it got a bad HCA score, a 68.2 depth is horribly deep. I saw this post at another site, the OP said it was GIA graded. I'm puzzled why GIA gave it an Excellent cut grade, maybe a more experienced PSer can chime in

 

[Korenne]

That should say 62.8. My bad. Thank you for pointing that out. However, the post still stands. at 62.8... it is marked as a 5.5 on the HCA with marks of Good, Good, Fair and Very Good. ... all of which are not very good for being an "ideal cut".

 

[hawk25]

Ah that makes more sense, I was thinking of suggesting that GIA terribly mis-graded that stone with a 68.2 depth

I believe that stone falls into the steep-deep category, which could explain the bad HCA score. Some steep deep diamonds have the drawback of appearing dark under the table.

There's a picture of a diamond with very similar specs (unknown depth) that shows off the potential drawbacks.

Page 3, Post #2 from James:
https://www.pricescope.com/forum/ro...ative-aspects-of-a-steep-deep-t129271-60.html

 

[JulieN]

An angle combo like that will certainly show leakage under an Ideal Scope. Probably a 36/40.8 combo is the highest you can go before the leakage starts getting bad. a 41.2 pavilion usually works better with a shallower crown.