Surprised by HCA and ACA Hearts and Arrows

[Kaili]

I just received a pair of A Cut Above Hearts and Arrows studs for Christmas, and I am overjoyed by the gift from my FI. I ran the specs through the HCA out of curiosity and was very surprised by the results.

I''ve been around the boards for awhile and I do understand that the HCA is one of many tools used to help eliminate poor performers and that it should not be used exclusively and not as a substitute for my eyes.

Both diamonds scored a 1.7 (yes, I know everything below a 2.0 is good), but I was surprised to see that the results on both "super ideal, A cut above, Hearts and Arrows, AGS 0" scored Ex/ VG/ VG/ VG. I would have thought that with their pedigree, they would have scored Excellent across the board.

Do the new generation ACAs not coordinate as well with the HCA because of a different cutting technique. Are they all like this?

Compared to my engagement ring diamond which is a non branded American 1b ideal cut, the studs are different. The studs are very white and seem to glow with their own light which is very pretty and makes them stand out on my ears. I do love them on my ears. In them, though, I do not see the disco ball effect that I see in my ring. They don''t seem to have much fire or sparkly flashes. They are a more constant glow.

I have read that the ACAs have larger flashes of light which may explain what I am seeing. I''m just wondering if my observations and numbers are typical of the ACA Hearts and Arrows?

Thanks

 

[Lynn B]

What are the sizes/specs on the diamond in your ring, and the studs?

 

[Kaili]

give me a minute and I will post them
Thanks for responding

 

[Kaili]

Ring:
.96 ct
G Color
SI 1
GIA Laser Inscribed
6.43 x 6.38 x 3.86mm
Modern Cut, closed culet
Medium faceted girdle
33.1 Crown Angle, 13.8% crown height
60.3% depth, 57.6% table, 43.2% pavillion depth
Excellent Polish and Symetry
AGA Cut Class: 1B, American Ideal Cut.
Slight Blue Fluorescence
HCA= .8, Excellent within TIC range

ACA Hearts and Arrows Stud #1:
Shape: A Cut Above H&A AGS 0
Carat: 0.502
Color: J
Clarity: VS2
Depth: 61.3
Table: 57
Crown Angle: 34.7
Crown %: 15
Pavilion Angle: 40.9
Pavilion %: 43
Girdle: Medium to Slightly Thick Faceted
Polish: Ideal
Symmetry: Ideal
Culet: Pointed
Fluorescence: Negligible
Measurements: 5.10-5.13X3.13

ACA Hearts and Arrows Stud #2:
Shape: A Cut Above H&A AGS 0
Carat: 0.505
Color: J
Clarity: VS2
Depth: 60.9
Table: 55
Crown Angle: 34.9
Crown %: 15.7
Pavilion Angle: 40.9
Pavilion %: 43.2
Girdle: Thin to Medium
Polish: Ideal
Symmetry: Ideal
Culet: Pointed
Fluorescence: Negligible
Measurements: 5.17-5.19X3.15

By the way, I am not complaining about my studs- I love them and I love that I was totally surprised by them. I am just trying to learn and understand, so that I know exactly what I want and what to look for on future diamond purchases.

 

[Lynn B]

Do you have the pav angle for the stone in the ring?

 

[Kaili]

sorry... I know better than that.
It is 41.0 degrees/ 43 %

 

[Lynn B]

OK... now that I have requested all that info, you are probably expecting me to have some profound pearls of wisdom in response to it all, huh?! Well, um, sorry!

Haha!

But, seriously, here's what I THINK may be happening. All 3 diamonds sound like killers to me. The shallower crown/slightly deep pav combo (which can be STUNNING!) on your e-ring is a little different than the ACAs -- and that slight nuance MAY be what you are seeing. Neither better or worse, just "different". And remember, every diamond is unique and has its own personality - just ask the experts who have the treat and luxury of viewing hundreds/thousands of stones!

There may also be some really technical aspects (LGF, star ratios, azimuth, yaw, etc.) - but that stuff goes WAAAAAY above my head. But maybe the experts can chime in with that?

Can you post some photos of the diamonds side-by-side? Although I doubt if the slight nuances you are seeing would be able to be picked up or even discerned by your camera and our computer monitors.

My advice? Totally enjoy all three of your stones, and savor each's "flavor"!

 

[Mara]

It''s actually very rare that you find a stone that scores EX across the board on HCA, it''s pretty strict on that last spread calculation...usually about 9 out of 10 diamonds I punch into the HCA will only have VG for spread.

You can do a bit of research on old HCA threads, there have been discussions on what the HCA prefers or penalizes for...aka that 40.9 pav angle (and the 41 pav angle in your ring stone) and maybe that 34.9 crown angle may be getting a bit of a penalty with the table and depth #''s. You can also play around with the HCA typing variations of your stones in to see what moves the score.

In reality, the HCA for me is just a tool to weed OUT bad performers aka a 3 or 4 or a 5 but for many people 2.5 and under is a subjective decision on what your eye finds beautiful.

 

[Kaili]

Thanks Lynn and Mara!

I do totally love all of my diamonds and it is cool that they have different personalities. Just by chance, I think I lucked out. I LOVE my ering diamond because it is crazy firey. People are always grabbing my hand because they can''t believe what a disco ball it is. I think I just totally lucked out there because on paper, it isn''t exactly perfect- Mark at Engagementringsdirect.com eyeballed it and we trusted him- I''m so glad we did.

I have tried to take photos, but unfortunately I just can''t seem to catch the properties in each of the stones with the camera. I''ll keep trying and see what I can come up with.

The diamonds studs are really suited to my ears because they just glow so consistently bright. My FI thinks they have some kind of property that makes them glow- I''m not going to burst his bubble

. I probably wouldn''t want the disco ball type stones on my ears.

I guess I didn''t understand how rare it was to get Excellent all the way across on the HCA since the 1B ering diamond scored all excellents. I just assumed that the ACAs were "better" instead of "different. "

For me the combinations are perfect by chance and I wouldn''t want them any other way.

This has been a great learning tool for me. Now I know that I like more firey stones with smaller flashes of light for certain items of jewelry, but not for all.

 

[strmrdr]

When I use the hca i usually ignore the Ex/ VG/ VG/ VG stuff.
The hca doesn''t take into account the lgf% which has a huge impact on how the diamond returns light nor does it account for the stars which have a smaller impact but can be important in some combos.
It also does not take into account girdle treatments.

The hca tells you if the average crown angle works well with the average pavilion angle.
Anything beyond that isnt accurate enough to be too useful in a lot of cases.

 

[Kaili]

great clarification Strmrdr! Thanks.

 

[Kaili]

I just can''t seem to capture on film what I am talking about, but here is my best shot.