Excellent rating from GIA...but not HCA? - 60% Table

[supra_888]

Hello,
I've been a long-time lurker in the shadows of this forum and greatly appreciate the wealth of knowledge that the forum and its posters provide.
I found a second-hand diamond ring that is selling for an attractive price of C$8,000 in Toronto, and even though the GIA specs look quite decent, the diamond didn't look too favorable through the HCA tool after plugging in the inputs.

GIA:
Round Brilliant
Measurements: 6.96 - 6.98 x 4.25 mm
Carat Weight: 1.27 carat
Color Grade: H
Clarity Grade: VS2
Cut Grade: Excellent

Proportions
Depth: 61.0%
Table: 60%
Crown Angle: 35.5°
Crown Height: 14.0%
Pavilion Angle: 41.0°
Pavilion Depth: 43.5%
Star Length: 50%
Lower Half: 75%
Girdle: Medium (3.5%)
Culet: None

The polish and symmetry were excellent and there was no fluorescence.

HCA Tool:
Factor: Grade
Light Return: Good
Fire: Good
Scintillation: Good
Spread or diameter for weight: Very Good
Total Visual Performance: 4.6 - Good - Only if price is your main criterion

Therefore, I'm wondering if I should be concerned due to the disconnect between GIA's "rating" and HCA's rating or if I should relax and rely on GIA. I will be seeing the diamond in person as well.

Thanks everyone for your help!

 

[JulieN]

8000 is not a good price at all for second hand. That is almost Internet retail price.

 

[milton333]

GIA has a very broad range of "excellent." HCA is geared toward targeting a more limited range of ideal performance.

What you're looking at is a 60/60 diamond. For a long time, this was kind of an industry standard shortcut to good cut grades. Some 60/60 diamonds can be lovely, but most on here would prefer a smaller table and steeper crown angle to get more colored light return or fire.

Also, I agree that the price seems a bit high. We can help you find a lovely stone, if you'd like to share budget and specs, and any preferences for settings.

 

[vishke8]

I agree, the price is too high for a second diamond.

I suggest you look for options over the internet or post your requirement, I am certain you will find the best deal and assistance on PS.

Goodluck

 

[Christina...]

I agree with the others regarding price. By purchasing second hand you're also giving up a number of valuable policies such as buy back, upgrade, and maybe even your ability to return the stone if you should change your mind after the purchase. Just something to consider.

 

[John P]

GIA has a very broad range of "excellent." HCA is geared toward targeting a more limited range of ideal performance.

What you're looking at is a 60/60 diamond. For a long time, this was kind of an industry standard shortcut to good cut grades. Some 60/60 diamonds can be lovely, but most on here would prefer a smaller table and steeper crown angle to get more colored light return or fire.

Also, I agree that the price seems a bit high. We can help you find a lovely stone, if you'd like to share budget and specs, and any preferences for settings.

As an aside, the 60/60 make came about as a combination of lighting changes and better yield. There was no grading of cut on consumer reports, so diamonds were often fashioned to look good under showroom lights. As high pressure lighting came into use in the later part of the 1900s retailers found larger tables, lower crowns and narrower pavilion mains made for extremely bright-looking stones when lit correctly. Conveniently for manufacturers, producing such diamonds - as opposed to the "Scientific Cut" adopted by Lazare Kaplan, Tiffany & Company and others some decades prior - also resulted in greater yield from most rough crystals.

60/60 makes are capable of earning EX and/or Ideal at GIA and AGS, although it takes skill since the "bullseye" window of complimentary angles is smaller than makes closer to modern Tolkowsky numbers.

 

[Karl_K]

Proportions
Depth: 61.0%
Table: 60%
Crown Angle: 35.5°
Crown Height: 14.0%
Pavilion Angle: 41.0°
Pavilion Depth: 43.5%
Star Length: 50%
Lower Half: 75%
Girdle: Medium (3.5%)
Culet: None

Because of the GIA rounding these numbers and the HCA are pretty much useless with this particular combo.
Within that range of gia rounding are possibly top of the line combos and some a step or 2 down from top end.
If shopping in person consider getting your own IS or ASET scope.

 

[Gypsy]

No way I would pay 8k for that. http://www.bluenile.com/ca/diamond-search?filter_id=0&pt=sig#diamonds_pid=LD02608130 or http://www.bluenile.com/ca/diamond-search?filter_id=0&pt=sig#diamonds_pid=LD02485821 buy one of these instead.

 

[Menlikediamondstoo]

Because of the GIA rounding these numbers and the HCA are pretty much useless with this particular combo.
Within that range of gia rounding are possibly top of the line combos and some a step or 2 down from top end.
If shopping in person consider getting your own IS or ASET scope.

Hi Karl,

I know this is an old thread, but I just wanted to let you know you put me at ease. When I was looking for my 2 carat round, I looked at 8 stones. Many scored very well on the HCA and one did not and had proporations very close to the diamond above. Guess which one I choose?!? it bothered me soo much that the HCA score was bad. I could have had an HCA under 1 but after looking at the stones, the one with the 60% was by far my favorite and just danced like crazy. All the stones were gia XXX and were all beautiful, but there was no comparison in terms of the 60% table. When you say the “HCA is pretty much uselesss with this combo” does that mean the stone could have a a great cut and just doesn’t work with the HCA guidelines? At the end of the day I have to remind myself that I choose my stone over many and shouldnt let a score number bother me!

Thank you for your feedback as always!

 

[Karl_K]

. When you say the “HCA is pretty much uselesss with this combo” does that mean the stone could have a a great cut and just doesn’t work with the HCA guidelines?

The GIA rounding then averaging then grossly rounding of the numbers is the issue.
Within the gia rounding on that combo is some with potential ags0 under 2 hca combos all the way out to off the top of my head an ags4 and somewhere around hca 4-5.

It sounds like you found one of the great ones!!

 

[Garry H (Cut Nut)]

Before digital scanning and hi tech planning which began in the early 1990's:

"You my son, I am going to give you the skills passed down through 5 generations. You take the diamond and saw as close as you can to the middle. Then you cut 2 equal sized diamonds. Make then as big as you can"
And hey presto - you get 2 60:60's