Great specs, bad HCA?

[irinarina]

Hi all,

My jeweler has just sent me the specs of the diamond, which are all within the range to eliminate bad light performance diamonds and give out a lower than 2.0 HCA score.
It's a hearts and arrows diamond. The specs are: 61.8 Depth, 57.8 Table, 35.6 Crown Angle, 40.7 Pavillion Angle.
I ran HCA and it gave me 2.2!

What might the issue be?


Thanks!!!

 

[MissGotRocks]

That is a very high crown angle. Preferred is 34 to 35. At 35.6, it probably gets dinged a bit on the HCA. With a crown angle of 35.2, you get an HCA score of 1.9.

Personally, I'd keep looking unless the stone has the look that you love. A HCA score of 2.2 doesn't necessarily mean you have to reject the stone entirely - just depends on what flavor of cut you are looking for.

 

[pfunk]

Hi all,

My jeweler has just sent me the specs of the diamond, which are all within the range to eliminate bad light performance diamonds and give out a lower than 2.0 HCA score.
It's a hearts and arrows diamond. The specs are: 61.8 Depth, 57.8 Table, 35.6 Crown Angle, 40.7 Pavillion Angle.
I ran HCA and it gave me 2.2!

What might the issue be?


Thanks!!!

It is quite possible that the diamond does have great light performance. I have seen quite a few AGS 0 stones with crown angles up around 35.5. The nature of the HCA as a rejection tool means it will rule out a good diamond from time to time. Its usefullness is that it is less likely to give a bad diamond a passing score than it is to give a good diamond a failing score. It wouldn't be as easy to use and as useful to consumers if it was commonly including diamonds with poor performance. Is this an AGS graded diamond?

 

[irinarina]

Yes, it's AGS graded. I have not seen the certificate yet. Once I get a copy I will post more info here.

 

[pfunk]

Yes, it's AGS graded. I have not seen the certificate yet. Once I get a copy I will post more info here.

Please do. If it is a performance based report and the diamond scores 0 for light performance it should be a beauty.

 

[Karl_K]

Those numbers depending on the specifics and the minor facets have the estimated potential to be anywhere from ags0 to ags2.
So a performance based report ags0 is not out of the question.
Because the hca does not take into account the possible minor facet variations it is cautious and returns the score of 2.2 which is pretty spot on if it was cut to the usual average specs which would result in an estimated ags1.

 

[diamondseeker2006]

2.2 is not bad. The stone may be perfectly fine, but it is one that would require an idealscope or ASET image for me to be certain.

 

[irinarina]

There's no photo in AGS certificate. I have an aset but I hoped to see the photo as I am not experienced in using aset. Any thoughts would be greatly appreciated!