Is an HCA of 6 always bad?

[Billy Mays]

I've been working with a "wholesaler" that is a family relation who has a very honest reputation, but all the stones he has shown have had high HCA scores. I visited at least 2 more wholesalers as well as scores of retailers to look at round cuts and nobody except for Michael S cared for the HCA or lightscopes, etc.

Anyway I told him my concerns on cut and he showed me Excellents and Ideals and I thought I had a good one until I saw the HCA score of 6. I have to decide by today if this stone is a good stone or fairly priced even or if I can do better for my money. He didn't have the stone in stock and visited the exchange to find someone else who did (he has to return it soon).

Could you guys kindly help me? I have spent so much time looking at stones in person and reading guides on this site that I feel overwhelmed and I would genuinely appreciate your input.

Price is $12,500 per ct. He has offered to let me take the stone wherever I want to have it appraised or to compare it even.

I forgot to bring in my lightscope today or I would have looked at it. But I ran it through the HCA and got a 6 (Fair for Light Return, Fire, Scintillation and Very Good for Spread).

GIA certified
2.03ct
G
VS2
Cut/Polish/Symmetry are all EX
The inclusions are very small, closer to a VS1 in fact, and mainly on the bottom so this is a very clean stone.
Measurements: 8.11 - 8.16 x 5.00 mm
Depth: 61.5%
Table: 59%
Crown Angle: 34.0°
Crown Height: 14.0%
Pavilion Angle: 41.6°
Pavilion Depth: 44.0%
Star Length: 45%
Lower Half: 85%
Girdle: Medium, Faceted (3.5%)
Culet: None


Thank you in advance,

A very overwhelmed guy.

 

[JulieN]

Yes, it is beyond all hope. Go directly to Jail. Do not pass Go. Do not collect $200.

 

[MichelleCarmen]

Sorry, I don't want to come across as unkind, but usually family relation doesn't necessarily mean the person is going to sell you a great diamond. In fact, often when people post here about diamonds being sold to them by friends-of-family and similar, the diamonds aren't that great or the deal isn't what it seems.

An HCA of 6 isn't a good score. There is no subtle way to put it. I would pass on the diamond unless you can look under your ideal scope and get see it actually looks ideal!

 

[kenny]

Only when the 6 is over 2.

 

[Billy Mays]

So really between 0-2, there is some subjectivity on what looks best but once you go above that, it truly is a bad stone, correct? Or at least with a 6 anyway.

 

[MichelleCarmen]

So really between 0-2, there is some subjectivity on what looks best but once you go above that, it truly is a bad stone, correct? Or at least with a 6 anyway.

Yes, it is a bad stone. If it sparkled, it was only because the lighting in the jewelry store is designed to make nearly EVERY diamond sparkle.

 

[Haven]

Only when the 6 is over 2.

Exactly.

It's important to remember that this family friend may not be trying scam you or sell you a less-than-great stone on purpose. Maybe this is just the type of stone he sells, maybe he just doesn't know any better. The good thing is--we do!

Pass on this stone. If I were you, I'd post your budget and desires in a new thread and see what PSers can find for you.

 

[Billy Mays]

Thank you all - I really do appreciate it.

 

[diamondseeker2006]

Billy, up to 2.5 or so is usually fine. Many of us also found shopping locally frustrating and ended up buying from vendors here that specialize in excellent cut stones. I just wouldn't deal with anyone who tries to sell you a poorly cut stone.

 

[Rockdiamond]

HI Billy, before you dump out the baby with the bathwater.....

HCA can predict a certain type of optical performance.
BUT- GIA is using different parameters- which is why you can have a stone that gets GIA's top grade, yet a poor score on the HCA.

I am sorry guys- but calling this a "bad" diamond - or saying it won't sparkle are really premature. Calling GIA triple EX "poorly cut" without ever seeing it is very misleading to the uninitiated. I would say that it's likely a very pretty diamond.
I agree that we can use the HCA to identify things we love. But some people will prefer the type of stone that this one might be- different from an H&A type pf contrast pattern- which is a more organized sparkle- but the longer LGF's might mean that this stone might actually be perceived as "sparkier"
I don't agree that a GIA graded triple EX diamond getting dinged by the HCA means it's a bad diamond. If given a choice, Billy might prefer this type of EX cut grade over one that scores lower on HCA

Billy, if you can see some "super ideal" stones in person, that would be a good idea.

+1 to Haven who mentioned that whoever is suggesting this stone to you has no idea what the HCA is- so assumptions about them trying to sell you a bad diamond knowingly may be incorrect.
I personally think any seller of well cut diamonds today should be aware of this debate- but most are not. For many people the GIA EX cut grade is enough.
You may or may not be one of those people

 

[Laila619]

That really steep pavilion angle of 41.6 is mainly what's causing the bad score. I'd pass!

 

[diamondseeker2006]

That really steep pavilion angle of 41.6 is mainly what's causing the bad score. I'd pass!

Yes, and that usually means a ring of leakage.

I think, though, that your specs and budget may not realistically work for an ideal cut stone. I think to go for G VS2 you'll be a little under 2 cts. and to go over 2 cts., you may need to go to H color or SI1 clarity.

http://www.goodoldgold.com/diamond/9802/

http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-2696797.htm

 

[Rockdiamond]

Did you notice anything like a ring of leakage in the middle of the diamond Billy?
You have the advantage of having seen the diamond first hand.
Any professional will tell you that stones need to be assessed in person. Making these type of judgments based on measurements is simply not accurate.
I have yet to see a diamond graded EX by GIA that has a leakage problem.

I happen to see the beauty in both the super ideals, as well as stone that may get GIA triple EX, yet score poorly on HCA.
Some people would prefer a smaller/darker / more imperfect diamond of "super ideal" cut, while others prefer a different type of cut, and would not trade size/clarity or color for a higher HCA score.
Neither is "right"

 

[Billy Mays]

Rockdiamond, you're really making me re-think this. I didn't have a light scope with me to determine leakage and was looking at it under office lights (not super bright jeweler lights). I'll see if I can stop by tonight to see it with the scope.

 

[Rockdiamond]

You're welcome Billy - please call me David

About the leakage:
1) every diamond leaks light
2) if you need a tool to see leakage, ....well....how significant is leakage that can't be seen naked eye?- Or it's possible that some leakage contributes to the look of a given stone.
Looking at night is actually good- as long as you can also get a good look in daylight/bright natural light scenarios.

 

[yssie]

LGF is 85 - could be higher w/ GIA rounding - perhaps not beyond redemption wrt outright "leakage" - the concern is the steeper lgfs leaking but they'll be shallower than on most stones that people use HCA on... it'll still be a different flavour of light return than another stone w/ shallower pav and shorter lgf.

Super long lgf is not a look I personally care for but cue Kenny: people vary

Edit make that cue Karl https://www.pricescope.com/journal/do_pavilion_mains_drive_light_return_modern_round_brilliant

 

[Dreamer_D]

In my opinion you should not completely throw out an option because of a high HCA if the daimond meets other criteria.

In particular, the diamond receiving a GIA Ex means it is not a dog. It is worth considering. Compare it to other stones that have both a GIA Ex and an HCA under 2, use your eyes in different lighting. Also, you can use an ideal scope to help evaluate the diamond. The HCA is one tool among many. If you want a very very precise type of cut, then yes, you should exclude any diamonds over a score of 2 on the HCA. But a GIA Ex is not something to throw away precipitously.

GIA rounds all of those numbers and that is why you cannot use the numbers as gospel. At some point, when you have narrowed the field appropriately, your eyes do matter too. In this case, use them and make an informed choice.

Also make sure the prce is fair using the search tool, above. Make sure the seller offers a no questions asked refund policy with an appropriate inspection period as well.

 

[kenny]

Super long lgf is not a look I personally care for but cue Kenny: people vary

True.
Some will get well cut diamonds.
Others will get poorly cut ones.

Live and let live?
Perhaps, but I thought this was a diamond education site.

 

[yssie]

Super long lgf is not a look I personally care for but cue Kenny: people vary

True.
Some will get well cut diamonds.
Others will get poorly cut ones.

Live and let live?
Perhaps, but I thought this was a diamond education site.

It might *not* be a poorly cut stone though Kenny - by the four inputs the HCA takes it's a leaky disaster, but taking LGF into account - very long LGF might just save it and prevent it from leaking overly. If he saw it IRL and compared it to other stones and loved it, then maybe the very long LGF "look"/type of light return is something he especially likes... if he didn't compare to other stones who knows. It's not *my* kind of stone - I'd want just the opposite.

 

[Lula]

Did you notice anything like a ring of leakage in the middle of the diamond Billy?
You have the advantage of having seen the diamond first hand.
Any professional will tell you that stones need to be assessed in person. Making these type of judgments based on measurements is simply not accurate.
I have yet to see a diamond graded EX by GIA that has a leakage problem.

I happen to see the beauty in both the super ideals, as well as stone that may get GIA triple EX, yet score poorly on HCA.
Some people would prefer a smaller/darker / more imperfect diamond of "super ideal" cut, while others prefer a different type of cut, and would not trade size/clarity or color for a higher HCA score.
Neither is "right"

I agree with David. The HCA cannot "see" the diamond. But you can. This diamond is outside of the very rigid PS "formula" and so many people here wouldn't even consider it, based on the numbers. But there is nothing inherently wrong with the numbers on this diamond.

I will not buy diamonds by the numbers, because, in my experience, it's how the angles work together that make a beautiful stone, not the numbers themselves. I've seen super-ideals that look dark to my eye, but are "perfect" by the numbers.

 

[JulieN]

It might perform better than HCA predicts, but what are the advantages of stone versus a BIC with long LGF and CA<32? (Not having DiamCalc, I think that is what it would take to "save" it.)

Or if David came on here and were a regular consumer instead of being in the trade in NYC, and he said he wanted a "smaller/darker" round and liked very long LGF, I would suggest a FIC over this.

 

[Rockdiamond]

Julie, when I said "smaller darker" I mean, comparing a 2.00 G/VS1 GIA triple EX scoring 6 on HCA to a 1.80ct G/VS1 super ideal. Or a 2.00ct I/SI1 Super ideal. IOW giving up color clarity or size to buy a diamond which is a better cut.

No matter if I'm in the trade or not, we can not classify this as a poorly cut diamond with the evidence at hand
I'm not saying Billy should buy the diamond. Just that we can't rule it out as an option with what we know.

I did not comment or study the price.
But let's agree that a hypothetical diamond graded Triple EX by GIA, yet scoring poorly on the HCA would not be classified as a "super ideal" by experts.
Most diamond dealers are not experts.
They would not, on average, think to use HCA, ASET, etc and the tools used here to select the very cream of the cream.
But let's say that most diamond dealers,and cutters know how to spot a badly cut diamond.
There's a level of tolerance in GIA's EX cut grade. Just because a diamond is not super ideal, does not mean it's badly cut.

Educate folks to understand that you can buy a really well cut GIA EX ( or even heaven forbid VG) cut grade and get a very well cut diamond.
There are a lot of poorly cut diamonds.
Not getting GIA EX cut grades.
So, we have a level of excellence-a and we can further educate people that there's a higher level of excellence.
Like a super fine wine, this added level of perfection may not even appeal to everyone- no matter it's price, or character.
But for those who want that extra level, and appreciate the optical properties that come along with it, there's price to pay.
I happen to see value in both.
Much like I see value in both IF stones, and VS1 stones. And I1 stones.

A consumer can educate the seller.
Tell them you understand that the very best cut- and I mean the very top of GIA AGS- will cost more- but you want to pay it. Then they will find it, or loose your business.

Educate people to look at both- but I have always believed it's wrong to scare people away from diamonds that are well cut, yet not super well cut by terming them poorly cut, or saying they'll have leakage, etc.....

 

[JulieN]

Thanks, I was hoping somebody would DiamCalc it.

 

[Dreamer_D]

Super long lgf is not a look I personally care for but cue Kenny: people vary

True.
Some will get well cut diamonds.
Others will get poorly cut ones.

Live and let live?
Perhaps, but I thought this was a diamond education site.

It is an exaggeration that is not in the best interest of consumer education to characterize a GIA Ex cut as "poorly cut".

 

[JulieN]

Galileo, I'm curious as to what the stereo light return value is for your example?

 

[Dreamer_D]

This is one of the poorest angle combinations that still gets a GIA Ex for cut grade.

It would appear to conserve weight and to ensure staying over the 2ct mark a steeper than optimal pavilion angle was utilized.
If it had perfect symmetry(it could look worse) this is what the Idealscope would look like.



Nothing wrong with buying it but you should check other GIA Ex diamonds to see if it is discounted enough in comparison.

This is a nice example of how every little bit of extra information helps a consumer make a decision. But, since this model is based on rounded and averaged numbers from the GIA report, I would still like to see the OP look for this type of poor performance in person using an ideal scope or, if not available, then his eyes comparing the stone to other diamonds that are GIA Ex AND also score well on the HCA.

The note about the carat weight is a good one. As a rule, I personally steer clear of diamonds right on the cusp like that. It is too "convenient" for us to assume the stone was cut for optics AND also happened to be right at 2ct on the nose.

 

[yssie]

The note about the carat weight is a good one. As a rule, I personally steer clear of diamonds right on the cusp like that. It is too "convenient" for us to assume the stone was cut for optics AND also happened to be right at 2ct on the nose.

The opposite is much more likely.
Assuming a typical sawn rough which yields two stones.

Take the maximum width of the rough and a maximum crown height of 14% which results in crown main angles of 34.
With crown mains at 34 Degrees the steepest pavilion angle that would still allow them to get GIA Ex cut grade is 41.6 and that is what they achieved. This scenario would make the most sense and would maximize value for the cutter but doesn't produce the brightest stones.

Good points - that's much more realistic than what I was envisioning. Thanks for the pic Galilleo.

 

[Billy Mays]

So I looked at it with the Light Scope. It did have leakage like you guys described. I have seen at least 75 stones in person yet but I'm not at the point where I remember the shine in one and can compare it to a shine in another I saw 2-3 days ago (I'm not sure I ever will be).

I do believe the guy in that he is genuine at not looking at HCA numbers or light scope when he buys since it doesn't usually factor into his business but I figure if I am paying out this money, I may as well get something a little better (not perfect, just better).

I work in finance so I'm pretty decent with numbers and I built an excel model to help me price the diamonds (I know it's imprecise, but it gives me ballparks using online inventories) but it doesn't account for HCA.

Let's say I am sitting in an office again and don't have my light scope and it looks bright because of the light but I can't tell if there is leakage. I won't have access to the HCA until I get home so are there certain angle combinations that I should look for instead of waiting until I am home?

Thank you.

 

[diamondseeker2006]

Billy, there are some measurements that usually will result in an ideal cut stone. YES, there are measurements outside these parameters that are nice as well. But to make life easier for those who just want to narrow down prospects to find an ideal cut stone, I use this:

table: 54-58

depth: 60.0-62.3

crown angle: 34-35

pavilion angle: 40.6-41.0

girdle: thin, medium, slightly thick (or combination of those)

 

[Billy Mays]

So the 1% difference in the table and the 0.6 degrees in the pavilion are what hurt this diamond? Something that small? Wow.