To those who bought diamonds (>> HCA=2.0), can you please share your testimonies on your great find

[haagen_dazs]

The diamond search is starting to wear me down at times ha! ...The tools that we have to narrow diamonds down are wonderful but the eyeball should be the final say .

I just cannot imagine how frustrating or antagonizing it must be for the sellers and companies to see their own diamond (posted by a buyer on PS for opinions) getting shot down for what amounts to not meeting "the various tool standards we use here"...

HCA can be useful to weed out non-promising diamonds with a score of >2.0.

So my question is, are there any testimonies from pricescopers who have bought a HCA >2.0 diamond that still performed wonderfully great? If you could elaborate why what how you came to that decision, that would be great..


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Tagging on to that
There is a diamond that someone told me to consider

It scores a HCA of 2.4
No asset or is images because the diamond is probably out on memo.


Quoting
From expert John Pollard.
With that said, here''s a "Cliff''s Notes" for staying near Tolkowsky/ideal angles with GIA reports (their numbers are rounded): A crown angle of 34.0, 34.5 or 35.0 is usually safe with a 40.8 pavilion angle. If pavilion angle = 40.6 lean toward a 34.5-35.0 crown. If pavilion angle = 41 lean toward a 34.0-34.5 crown.

GIA "EX" in cut is great at its heart, but it ranges a bit wider than some people prefer, particularly in deep combinations (pavilion > 41 with crown > 35).


Why is it that this diamond, still falling within the ranges, is not "getting a great HCA" score?


Report: GIA
Shape: Round
Carat: 1.28
Color: H
Clarity: SI2
Cut: Excellent
Measurements: 6.89-6.96X4.29
Depth Percentage: 61.90
Table Percentage: 59.00
Crown Angle : 34.5
Pavilion Angle : 41.0
Star length : 60%
Lower half : 75%
Lower hal
Girdle: Medium to Slightly Thick
Polish: Excellent
Symmetry: Excellent
Fluorescence: None
Culet: None
Certificate #: 2106454572

 

[kenny]

Date: 10/7/2009 6:13:44 PM
Author:haagen_dazs

So my question is, are there any testimonies from pricescopers who have bought a HCA >2.0 diamond that still performed wonderfully great?

Define wonderfully great.

Even if poster X says, "My HCA 2.7 diamond is just beautiful." - How useful is that?

You've been here a while.
Picking a round is not that hard- much easier than other cuts.
You sound like you have analyses paralysis.

Or maybe, like many shoppers, you've decided you MUST have specs that are JUST beyond your reach for your budget.
If that's the case bring your expectations into line with reality and just buy one.

I only mention this because you wrote that the diamond search is wearing your down.

 

[elle_chris]

Re: "Why is this diamond, still falling within the ranges, is not "getting a great HCA" score

Two reasons. First is the table, at 59 it falls outside of the ideal range. If you change the table to a 57 it''ll score under 2 but to be honest, that won''t be the deciding factor in how the diamond performs.
The second reason is the crown and pavilion angle. By lowering the crown to a 34, it scores better with the pavilion at 41. Or vice versa, lower the pavilion and keep the crown at 34.5 and again it scores under 2. Either way, this stone doesn''t have "ideal" proportions like you''re used to seeing here. It doesn''t mean it''s a bad diamond. In fact, it''s probably a very pretty stone. But an IS would help evaluate it further.

The ranges are just that, ranges. They still need to work well together.

 

[haagen_dazs]

Date: 10/7/2009 7:50:30 PM
Author: elle_chris
Re: ''Why is this diamond, still falling within the ranges, is not ''getting a great HCA'' score

But an IS would help evaluate it further.

yup i did get an aset and is ..
i started another thread on it

elle ; if you can give your input on my other thread, that would be great

 

[asforhim]

The thing to keep in mind is that the HCA is just another tool in an arsenal. You are right that the eye is the final beholder of beauty. The vast majority of diamonds that fall into the ideal or near ideal ranges are excedingly difficult to tell from one another by the naked eye. I personally own 3 ct studs (Harry Winston), one of which is an EX cut and the other VG cut by GIA standards. The VG cut scores 1.7 on the HCA and the EX cut scores close to 5 (no, I did not mix them up). I, and all the "experts" that have seen them, cannot tell which diamond is which by the naked eye. And they are incredible....

What I''m trying to say is that there are many diamonds with high HCA scores that perfom magnificantly... and I''m sure there are many with low scores that are not so great. I will never buy a diamond without seeing it first... I guess I''m old-school when it comes to this crowd.

 

[yssie]

Here's my take on this:

You're looking for a pretty common size, shape, colour, and clarity combo. We have these tools at our disposal, so why take a risk when you don't have to? If you were looking at 3+ cts, you'd have a much smaller selection, so you might have to compromise a bit...


ETA: that's not to say there aren't beautiful diamonds outside these parametres, and I reckon I'd trust DBL's judgment over my own in a heartbeat, for example. BUT for those of us new to this, without years of experience picking the beauties out of a parcel, tools like the HCA make our lives easier, when used as they are meant to be.

 

[Lula]

You've gotten some great advice on this thread, Haagen.

I'll add my .02, and say you can easily put yourself out of your HCA misery by going with a vendor who sells diamonds that are cut in an intentional and consistent manner, so that each stone the vendor produces performs well on the tools and is pleasing to the eye. No guess work.

BGD, Whiteflash ACA, Crafted by Infinity (through Wink or another Infinity vendor of your choice) are three that come to mind. Jonathan from GOG also carries stones cut to perform in a specific and consistent manner. Some of these vendors will produce videos for you, too, so you can see the stone on its own and compared to other stones. Wink made a video for me of two Infinity stones I was considering.

Again, no guesswork involved.

As elle-chris said, all of the angles have to work together, to produce a beautiful stone, which is why your goal of finding an "HCA > 2 great find" stone is proving to be illusive.

As many on this thread have mentioned, there are several ways of going about determining how well a stone will perform (ETA: and if it will please your eyes):

1. You can let your eyes do the deciding to determine if the angles "work together" in a way that pleases you. You have to live with the stone for a while under various lighting conditions to really judge how well it performs. You could forget buying a stone using the HCA and other tools, and go visit some B&M stores and view as many stones as possible. You can also order one of the stones you mentioned above as being "shot down" by posters, and see how it does in real life. Again, forget about the tools and buy what you like based on appearance. Send it back if it does not please you.

2. You can use technology to help you narrow the field and chose from several contenders that have good potential to please your eye when you receive them. If the stone does not please your eye, you have the option of sending it back and starting over. This is why the online vendors have good return policies. I returned a stone because it did not please my eyes. I don't think it's a big deal to spend a few bucks on shipping when thousands of dollars are at stake.

3. You can buy a stone from a vendor who sells stones that are cut in an intentional and consistent manner, as I mentioned above. These stones are cut to maximize visual beauty rather than to maximize carat weight. They are not "accidentally" beautiful (the HCA > 2 "great find"); they are cut to be intentionally beautiful. They cost a bit more, but in my experience, they greatly simplify the buying experience.

If cut is what's most important to you, I suggest that you look for the best cut you can afford, and lower your clarity and color, and perhaps carat weight, standards a bit to get a stone that will fit in your budget.

There are, unfortunately, no shortcuts to this process, and you risk even more frustration if you keep focusing on the illusive "good deal."

 

[FB.]

It is my belief that although the HCA gives an indication of how well a stone performs, the fine details depend upon the minor facets - star length, lower halves, symmetry and so on. In fact, it is recommended as a screening test and not final selection.

I posted the following:

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".......If we took a selection of diamonds of varying cut grades - such as Ideal(AGS-0), GIA-Ex, GIA-VG, GIA-Gd - roughly how much difference in light performance would be expected?
Or...how about HCA scores; 1-2 compared to 3-4 or 5-6?
I appreciate that there is some stone-by-stone considerations to be made, but how does the typical specimen within each group perform?



Just how much better would you say an ideal cut perform, compared to an Excellent or Very Good cut?
My experiences of comparing diamonds suggest that ideal cuts are better, but not so much better that all other cut grades must be avoided.

I'll start the ball rolling with my own perception of real-world light handling in a variety of conditions (marks out of 10 for how they look).

Ideal: 9
GIA-Ex: 8
GIA-VG: 7
GIA-Gd: 6

Basically, I'm saying that I can see a difference, but not such a difference as many people make it sound.

I feel that I am conditioned to believe - from what other people say - that the cut grades give the following:

Ideal: 9
GIA-Ex: 7
GIA-VG: 5
GIA-Gd: 3

Basically, the message from many people seems to be: forget anything less than ideal and try for super-ideal.

My own experiences suggest that even the lowly-regarded "Very good" cut grades can look very nearly as good as ideal, to the average person, in many conditions.

I'd be interested to hear others views.

FB
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Original thread here:
https://www.pricescope.com/community/threads/light-performance-and-cut-grade.125245/

Basically, the better the cut, the more light is reflected in the correct direction, which is generally considered to be straight up. As the angles get less complementary in the lower cut grades, you either get more light leaking out the bottom (as a result of steep pavilion angle that doesn't match the crown angle), or the crown and pavilion angles cause the light to be more scattered out of the top in various directions, instead of coming straight back out at you. But if you're standing off to the side of the stone, in some conditions and from some viewing angles, an ideal can look worse than a very good.

Imagine a diamond's light reflections to be like a hosepipe with the adjustable nozzle. You can have a scattered fine spray of water (a good cut), or a concentrated blast (a super-ideal cut).

Regards
FB