Is the HCA Score Always Reliable For Diamond Selection?
For most online shoppers, you might have come across a diamond performance predictor called the HCA (Holloway Cut Advisor) tool to help you make your selections. This was a question which was posed to us about using the tool.
“Recently, I had some diamonds sent in for a physical review for light performance at James Allen.
Here’s the 2nd diamond…
When the gemologist gave me the report, I was surprised!
The better diamond was the 0.42 carat-I-SI1 diamond (1475263) due to its superb light performance with the great fire, brilliance and scintillation. It faces up completely eye clean and has a nice white color. The 0.41 carat-H-SI1 diamond (14753031) had just ok light performance. It faces up eye clean and has a nice white color, but it just doesn’t perform as good.”
I can’t understand how a HCA of 2.6 can be considered superb light performance with the great fire, brilliance and scintillation compared to the H of 1.1 & 1.4.
Isn’t it supposed to be simple geometry & physics of light reflection / refraction?
Answer: The HCA scores only act as a guideline and should be used as a rejection tool rather than a selection tool. Think of it this way. If the HCA score for a diamond is < 2.0, it results in a higher probability of finding a nice diamond. For HCA scores > 2.0, the chances of finding a great diamond are smaller. However, that’s not to say beautiful diamonds with an HCA score greater than 2 don’t exist.
Most people take the easier way and simply ignore scores higher than 2.0.
For example, if you choose to shop at Bluenile or any other online vendor where there are no pictures or sufficient data – most shoppers are shopping based only on the information found in a grading report. They would rather ‘play safe’ and ignore scores above 2.0 because they don’t have access to tools like idealscope or even better, an in-house review of the diamonds.
Personally, I believe that HCA by itself shouldn’t be used as an end all be all kind of tool but rather as a screening system to narrow down your diamond choices.
Let Me Show You Why the HCA Tool Isn’t Fool Proof
I want you to check out the GIA report of this diamond with “great” looking proportions on paper. It’s a GIA triple excellent and there are no red flags based on the information presented in the GIA certificate.
These are the corresponding images for the stone…
Plugging in the proportions of the diamond into the HCA software…
As you can see in the screenshot above, the HCA tool returns an excellent score of 1.6 for Total Visual Performance and describes the stone as “Excellent within TIC range”.
Now, if you were to be using the tool blindly (and wrongly) without looking at other data like videos/diamonds images/scope photographs, you would be assuming that another diamond with the same HCA score is going to be identical and going to perform well.
In real life, things are going to be way different.
I would like you to take a look at the following diamonds. They each have identical table %, depth %, crown angles and pavilion angles compared to the diamond above. (Just to be clear, these are arbitrary examples. You can easily do a similar test on another set of diamonds with identical parameters yourself.)
To state the obvious, they will all have the same exact HCA score since the parameters used are the same (62.3 % depth/56 % table/ 35.0 crown angles/40.8 pavilion angles).
GIA certified H VS2 diamond report number #3265097097
GIA certified F SI1 diamond report number #2258954393
GIA certified H VS2 diamond report number #6183574691
GIA certified G VS2 diamond report number #7268215324
Do these diamonds all look the same to you? Even though the HCA tool returns the same exact score (Excellent – 1.6) for these diamonds, they obviously look different from each other!
For the record, let me tell you that None of these diamonds would make the cut to be purchase worthy if I were shopping for myself.
At times, the Holloway Cut Adviser fails to eliminate diamonds that aren’t cut for the best optical performance or have bad contrast patterning. This should come as no surprise since the tool itself is meant to be used as a weeding tool instead of a selection tool.
I could go on and on to list hundreds of examples to show the pitfalls of using the HCA software blindly if you are a discerning buyer. I will restate: the HCA tool was designed as a REJECTION TOOL and never as a selection tool.
Why The HCA Score For Diamond Selection Isn’t Everything
I will attempt to explain in plain English on some of the limitations of HCA:
1) HCA uses the average values of proportions/angles to generate its results. By doing this, the software is assuming a diamond that is perfectly symmetrical. In reality, diamonds have slight variations and deviations in the angles they are cut to.
If you have access to a Helium or Sarin Scan, you will see the deviations of the facet proportions. If you think about it, anything that is “human-made” will not be exactly the same. Furthermore, we are talking about cutting the hardest substance on Earth. There are bound to be degrees of inconsistencies in the diamond.
Sample Report of a Sarin Scan
When we are talking about diamonds, even a slight change in angles (<1 degree) can change the outlook of the stone and its performance.
2) Minor facets (lower girdle, upper girdle and star facets) are not taken into account during computation. For example, in real life, the length of lower girdle facets can impact how a diamond behaves under different lightings. A shorter lower girdle facet length would create broader flashes of light and a longer girdle facet length will create more pin flashes of light.
3) Inclusions and other properties. The software doesn’t take into account how inclusions can impact a diamond’s beauty. For example, it doesn’t tell you whether additional clouds are causing haziness issues in your stone or whether that crystal under the table facet is visible to the naked eye. Likewise, the HCA isn’t going to tell you if fluorescence has a negative impact on the appearance of the stone .
That said, diamonds themselves can have slightly different personalities even if they have ideal optics. For earrings, it would be best to match the diamonds to look similar. Since you had a professional gemologist review your choices at James Allen, they are your ‘eyes’ to help you select diamonds.
I think you need to give James Allen a call to discuss your concerns with them. They are the ones who had seen the diamonds physically and will be in the best position to provide you with further advice. Personally, I would trust what the gemologist says more than what the HCA scores tell me.
Paul
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62 Comments
I tried inputting the data for a shortlisted stone from Kay-Jeweler here but couldn’t do so due to the lack of data. Can you help?
It is a Leo Cut with 1.55 Carat Weight I Color and SI2 clarity.
Below is the grading report that accompanies the diamond.
Harry
The HCA tool is only applicable to 57 (58) facets round brilliant cuts. For the Leo diamond, it is a branded cut and cannot be used for assessment with the Hollway Cut Advisor.
Thanks for the clarification!
What do you think of the Leo cut and the choice that I had shortlisted?
Have you seen the stone in person? When people go for branded cuts, it is usually a preference for how the diamond looks like in appearance.
With that said, here’s my opinion on it:
The magnified picture shows a stone with very poor optical symmetry. The Leo cut is a joke and is overpriced for the kind of quality it offers. Shopping at Kay Jewelers will guarantee that you will be overpaying significantly.
In addition, the grading report for the diamond comes from an unknown source. Gemological Science International is totally unheard of to me. Why do you think the diamond was not sent to renowned labs GIA or AGS for grading? Is there something that they are hiding?
Chances are, the stone is graded loosely much like the case of IGI or EGL stones. When jewelers choose to use grading labs like these, I will usually avoid them since you won’t know exactly what you would be getting. They graded this particular stone as a SI2, it looks more like an I1-I2 by GIA’s standards at best.
https://beyond4cs.com/grading/difference-between-gia-ags-egl-igi/
Most of the time, these reports helps the jewelers sell rings for more at the expense of un-educated consumers.
https://beyond4cs.com/loose-diamonds/grade-bumping-scams/
What do you think of pricescope.com members swearing by HCA and pushing this tool as a decision maker? I have seen plenty of people be discouraged from buying certain stones based solely on these numbers before being seeing in person. After working for a jeweler I have seen pricescope advised newbies coming in to see diamonds and basing their choices on the HCA number vs. the actually brilliance and quality of the stone.
With all due respect, most people on such community boards don’t exactly know what they are doing or have a proper understanding about diamonds. Sometimes, even though the intention is good, some advice that is dished out actually does more harm than good but I digress.
Anyway, the HCA tool is pretty basic and it jives well with people who are clueless about buying diamonds. This is because it gives them some tangible data about a diamond’s performance even though it only makes use of limited data inputs to do so.
I personally don’t think it is an end all be all kind of tool. The thing about lay people trusting their own eyes when viewing a diamond physically is that lighting conditions can sometimes be manipulated and misleading in itself. i.e. poorly cut diamonds can actually be made to look nicer under certain types of lighting.
Where possible, I do recommend obtaining as much data about a diamond as possible. This includes viewing diamonds in various kinds of lighting condition for prolong periods of time, ASET, Idealscope, HCA score and etc… Granted, it may not always be possible because of physical constraints especially when it comes to buying diamonds online.
Hi Paul,
Is there ever an occurrence where the opposite is true? For instance, I have been looking at several GIA triple excellent reports, for an upcoming purchase. Using the HCA score as a guide, I have never seen anything lower than a 2.3. Is it possible to have a case where the HCA yields a higher score (i.e. 5 or 6) on a triple excellent cut, but the diamond has high brilliance potential in reality? Thanks for the guidance, and great site!
Yosh
I haven’t seen any diamonds with high HCA scores that have great light performance. In a way, the Holloway Cut Advisor weeds out the lousy stones but it doesn’t help you pick out the great stones. You’ll need an ASET or Idealscope for this purpose.
Hi Paul,
Thoughts on these two stones?
https://www.jamesallen.com/loose-diamonds/round-cut/0.91-carat-g-color-vs2-clarity-excellent-cut-sku-1016284
https://www.jamesallen.com/loose-diamonds/round-cut/0.90-carat-g-color-vs2-clarity-excellent-cut-sku-1054067
Thanks!
Both are mediocre stones.
Hi Paul,
Thanks for getting back so quickly. I am surprised at your opinion. Will you please elaborate as to why your consider both of these mediocre?
I am in the process of deciding between these two and thought specwise they are excellent.
Experience. Once you viewed enough diamonds and correlate them to real life light performances, you will be able to do it too.
Proportions wise, both have already failed my 1st stage of filtering. The videos simply confirmed it.
Ok, hole you didn’t take offense to my previous comment…not judging your opinion at all. I have found your recommendations for proportions and am having James Allen search for a stone that meets the specs. For 1026284, will you please tell me which specifications in your opinion make it fail in your first stage?
Thanks!
None taken. I’m trying to be objective in my comments.
Read these: https://beyond4cs.com/shapes/round/ideal-proportions/
https://beyond4cs.com/step-by-step-guide/
Paul,
Could you please tell me which is a better stone in terms of sparkle and colour (appear most white)? it will be in yellow gold setting, I would go with the K diamond, but a little afraid of it looking yellow. Some people are saying it might appear yellow. What do you think? What do you think is the best deal for the price and performance? Sorry for so many questions, but as an expert I think you know better than anyone I know. I really appreciate the help. Thank you!!
https://www.jamesallen.com/loose-diamonds/round-cut/0.72-carat-k-color-vs1-clarity-excellent-cut-sku-1020458
https://www.jamesallen.com/loose-diamonds/round-cut/0.73-carat-j-color-vs2-clarity-excellent-cut-sku-1137180
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3634229.htm
Without a doubt, this is the best diamond: https://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3634229.htm
Hi paul,
I am really having difficulty comparing diamonds in store to online. Could you please give me some advice on the better of these diamonds?
Instore diamond
https://www.gia.edu/report-check?reportno=3225002577
Online diamond
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3685704.htm
I realize how much better the whiteflash one grades on the HCA, but my girlfriend saw the GIA stone and loves it. Shold I be worrying about appeasing her or will the whiteflash stone make a significant difference in a rose gold halo? Both are in the same price range.
Thank you!
One is a poorly cut diamond while the other White Flash option is fantastic.
Thank you very much, one last question,
How about ranking these three?
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3365320.htm
http://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3685704.htm
https://www.gia.edu/report-check?reportno=2207681816
GIA 2207681816
thanks again for providing some clarity in an otherwise confusing engagement shopping world.
This would be the only diamond that passes my cut standards to be purchase worthy.
https://www.whiteflash.com/loose-diamonds/round-cut-loose-diamond-3685704.htm
The other White Flash diamond isn’t well cut enough and there’s no supporting cut information for the other unknown stone.
Hi Paul,
Would you recommend this stone just based off GIA report.
https://www.gia.edu/report-check?reportno=2141066141
Also, should grading date be something I should be concerned about?
Thanks
No. Proportions aren’t ideal.
Secondly, yes. The dated report may be a concern. I want to know why it is dated so long ago if I were shopping for a diamond myself.
Hi Paul
between the 2, what so you believe the better stone is if any are worthy of purchasing
https://www.jamesallen.com/loose-diamonds/round-cut/0.90-carat-h-color-si2-clarity-excellent-cut-sku-1804828
https://www.jamesallen.com/loose-diamonds/round-cut/0.90-carat-h-color-si2-clarity-excellent-cut-sku-1762914
Thank you
The first diamond is the better option in terms of cut quality. The feather may not be eyeclean though.
Thank you Paul for your quick and honest response,
I don’t even want to question if the diamond will be eye clean or not so i have decided to disregard sl2 and try to look for an eye clean sl1,
i have found 2 more that are very similar in specs but again not sure which one will perform better.
https://www.jamesallen.com/loose-diamonds/round-cut/0.91-carat-h-color-si1-clarity-excellent-cut-sku-1896831
https://www.jamesallen.com/loose-diamonds/round-cut/0.91-carat-h-color-si1-clarity-excellent-cut-sku-630268
personally i think the 1st one but i really don’t know,
Cheers,
Neither. You are running around in circles. I did a search for you and would recommend this stone: https://www.jamesallen.com/loose-diamonds/round-cut/0.90-carat-g-color-vs2-clarity-excellent-cut-sku-1844151
Hi Paul,
Relying on Enchanted info is a bad move. e.g the 1.5ct G SI1 – no way does the stone photographed match the 61% table on the GIA cert. I am happy to have HCA criticized, but please use some stones in your hand rather than mixed up sources like the ones you have used.
Kind regards
Garry Holloway
Hey Gary,
Thanks for dropping by and leaving your comment. I’ve checked the url listing again. Gosh, I did make a mistake there and slipped up by assuming the images were correct without doing a proper verification against the proportions. I’ve updated the post.
Paul
Hi Paul. Thanks for sharing your expertise! Do you consider the pavilion angle of 41.4 in the following stone a deal breaker? Thanks so much for your input.
Round brilliant graded by GIA as follows:
.80
Cut Ex
Symmetry Ex
Polish Ex
Depth perc. 61.8
Table percentage 56
Crown Angle 34.5
Pavilion Angle 41.4
No fluorescence
Thin to medium girdle
Thanks so much. I appreciate your input!
Yes. It definitely is. There’s no way I would even consider buying a diamond with these proportions.
Thanks so much for your input! I needed confirmation that I should steer clear of it. I am curious… If the pavilion angle was less steep (say 40.9 or so) would this be a decent stone? (all other proportions equal) Thanks!
Read this: https://beyond4cs.com/buying-diamonds-blind/
Hi Paul – very informative website!
Here is an example of a diamond that gets 4 Excellents on the HCA (is this quite rare?).
https://www.jamesallen.com/mobile/loose-diamonds/round-cut/1.00-carat-i-color-vs2-clarity-excellent-cut-sku-1953420
Is it worth following up with an ASET image, or do you think the symmetry will mean it’s not a great performer?
Any comments welcome!
Thanks
Christian
I can tell you that this diamond is going to be bright and will have good light performance. The symmetry will not impact the light performance much in this particular case. However, the proportions of this diamond 59/59 will result in a different sparkle/scintillation pattern compared to a typical ideal cut diamond that I would buy. The 59% depth is the reason why the HCA rating rewarded it for spread but it isn’t a good enough reason for me to buy it.
Hi Paul,
I’m looking to purchase a diamond from bluenile.com
I need your advice on it as soon as possible, and also if you have any information about the credibility of the site as well. I’m not confident in purchasing a diamond online and would appreciate your help.
Down below is the link of the diamond I have in mind
http://www.bluenile.com/diamond-details/LD06703289
Thank you
It’s a decent stone but not well cut enough by my standards. I did a search for you and would recommend these diamonds instead:
https://www.bluenile.com/diamond-details/LD06199853
https://www.bluenile.com/diamond-details/LD06832897
GIA 2247184620 $2900
GIA 1245017666 $2670
GIA 7238160368 $2600
Bluenile diamonds. I am deciding to buy all 3 and have them evaluated for light performance. What would you suggest for how this is done as I could not find a site that links me a “local” specialist. lastly, w/o having seen them or imaging, are there any concerns regarding their inclusions?
Bill
I hate it when people abuse a vendor’s return policy this way. It creates unnecessary costs for them, hassle for yourself and costs for yourself too. It’s not that hard; just that with their signature line and you saved all your trouble.
https://beyond4cs.com/reviews/blue-nile/signature-diamond/
Hi Paul. Great site! I’m interested in getting one and would like your advice. Here is an example of a diamond that gets 4 Excellents and a score of 0.6 on the HCA (is this quite rare?).
Round brilliant graded by GIA as follows:
Carat Weight 1.14 carat
Depth 60.0 %
Table 57 %
Crown Angle 33.0°
Crown Height 14.0%
Pavilion Angle 41.0°
Pavilion Depth 43.5%
Star Length 55%
Lower Half 80%
Girdle – Thin to Medium, Faceted, 3.0%
Culet None
FINISH
Polish Excellent
Symmetry Excellent
Fluorescence None
Is this a good & nice looking diamond?or do you think the symmetry will mean it’s not a great performer? Thanks so much. Really appreciate your input!
Cathy
The HCA rewards shallow diamonds which is why it scored 4 excellents. That said, I’m not of a fan of the shallow depth and crown angles. Those 2 numbers by themselves will cause me to immediately reject the stone.
Hello Paul,
Great site!
I was completely noob just few days ago but then I started to read all your website to understand more about diamonds But now I need your help because I think that I’ve made a mistake.
Here are the specs of the diamond I have just ordered :
GIA
Triple Excellent
VS2
F
0.87 carat
Fluorescence None
Depth: 62.5
Table: 57
Crown Angle: 35.5
Pavilion Angle: 41.0
Medium-slightly thick girdle – 4.0%
Inclusions: Crystal
HCA 4.0
But after purchasing it I discover the HCA tool and I have been a bit disappointed as the diamond I’ve order had only HCA 4.0
So I call the jeweler but he didn’t even know what HCA is!
At the beginning i was hesitating with a diamond with approximatively the same specs but in G color. I’ve chosen the first one because the only difference that I saw was the color and the clarity characteristics. But now that I know HCA tool I’ve seen that the second diamond had a better HCA score with 1.3.
Here are the specs of the second diamond
GIA
Triple Excellent
VS2
G
0.87 carat
Depth: 60.0
Table: 59
Crown Angle: 34.0
Pavilion Angle: 40.8
Thin Medium girdle – 3.0%
Inclusions: Feather, Cloud, Crystal
HCA : 1.3
The Jeweler said that both are triple excellent and that I will not see any differences with the naked eye. But now I have a doubt.
What do you think? Do I Have to change my order?
Will I see more difference between G or F color? or between HCA 1.3 vs 4.0 ? Do the inclusions of the second diamond (feather, cloud, crystal) can be an issue?
Thank you and sorry for my english
Fred
Both aren’t diamonds I would even consider because of their proportions. They instantly fail my first stage of filtering out stones without even having to look at further details.
Thank you very much Paul for your answer. The jeweler proposed me a new diamond
https://www.gia.edu/report-check?reportno=2246479935
Do you think that this one is a bit better? HCA score is 1.7
Thank you
Nope it isn’t. Table size is a tad too large. You need to read every single word of this article too: https://beyond4cs.com/buying-diamonds-blind/
Yes I know that one of the criteria doesn’t respect your guidelines. The table is a tad too large, 58% instead of 54-57%. But can we consider that this diamond is potentialy the least worst of the three ? Or all the three are as bad as the others ?
It’s OK if you want to justify your purchase or shortlisted items. I had already said my piece on it. At the same time, you should be asking why you want to do so in limiting yourself when there are literally hundreds of better diamonds in the market to begin with.
Beause I’ve already pay the jeweler for the diamond and because these diamonds were the least worst he proposed to me.
I know I could buy ACA on a website like whiteflash, but I already have experience in importation of diamonds and it’s complicated with the customs, tax etc… the last time I had to pay 15% of the diamond’s price to clear it at the airport and then 20% of vat…
The VAT and custom taxes are all included regardless of buying online or offline. It’s whether you want to see it broken down in parts or lumped together in the price offered by a local vendor.
You should probably re-read this again: https://beyond4cs.com/buying-diamonds-blind/
Anyway, the milk has already been spilled (should have done research before laying down a cent) and as I mentioned earlier, None of the diamonds would even make it pass my first step of curation. That’s how strict I am in weeding out mediocre diamonds.
First of all, terrific site.
Looking to purchase a .4 carat diamond, my local supplier has the below for about $1,000. Will this pass your standards?
He also mentioned it has 88 facets, hence the Angel 88 marking. Is this an actual game changing characteristic or more of a marketing feature?
http://www.agslab.com/pdf_sync_reports/104087537001-GDQRNC.PDF
I really don’t care for anything about these types of modified diamond cuts.
https://beyond4cs.com/faq/diamond-brands/
Hi Paul,
I came across this thread and was wondering if you could help with a decision we’re struggling to make, due to the blind aspect of online diamond shopping.
What do you think of the below diamond?
Too good to be true?
https://www.bluenile.com/build-your-own-ring/diamond-details/LD08325926
Thanks a lot – much appreciated!
Cutwise, the diamond is a little deep and it has strong fluorescence. These are factors that attribute the lower price point. I think it is a decent stone for the cost. Personally, I would want the cut quality to be as best as it could be.
I am looking at these two stones for stud earrings. The GIA certs are great, triple “ex’s” and the HCA scores are 1.1 and 1.2 respectively.
They are priced at $4,040 and $4,300. What do you think?
GIA #’s: 3245863597 and 7152546821
Thank you!
David
Read this: https://beyond4cs.com/buying-diamonds-blind/
Hi Paul,
when are you going to fix this? It is now a year over due!
And what’s your problem with it? The issue with the previous listing was already updated more 9 months ago.
The HCA score for this diamond is 0.7. Isn’t this supposed to be a great stone? It’s SKU R130-584242495 at ED. The grading report is here: https://www.gia.edu/report-check?reportno=3285016986
Well, the HCA tool is getting useless and outdated in today’s shopping environment. Your example only reinforces the reason why the tool fails and serves to confuse more than it helps. So what if the diamond achieved a super low score of 0.7? It doesn’t mean anything and if you had gone by to rely on the tool to buy the diamond, you just gotten yourself a poorly cut stone.
Look at the dug out areas indicated by the ASET. And that’s why I value tangible data more than whatever useless numbers the tool spits out. Back then when jewelers only sold diamonds based on a grading report, the tool might still have some use. Times changed. The tool didn’t.
I was over the moon happy with my diamond until I heard about HCA. My diamond scored a 5.6 and I am shocked. I think the light performance is excellent and get compliments and stares all the time. I have a 1.13ct, vvs2, E color, triple excellent diamond with no fluorescent. Is it possible to have a beautiful diamond with a horrible score?!
Depth: 62.2
Table: 58
Crown angle: 36
Pavilion: 41
Well, as I had time and time again been mentioning, the HCA tool is useless for many aspects of selection. And I think you may have inputted the figures wrongly. Regardless, if you want to know the performance of your diamond, use proper tools like the ASET to do so.
Hi Paul, I requested for ASET/Idealscope images from James Allen but was told that they’re not available? How should I proceed with the selection process? I’ve only got the 360 videos and am unsure of what to look out for. Many thanks!
Due to the COVID situation and the hardware setups of James Allen’s upstream diamond cutting houses, they may not be able to offer these scope images for some of their diamonds. However, performance and cut quality can still be assessed from the video listings with experience. If you have direct url links to the diamonds you are looking at, feel free to share them with me as I can help you take a look at them for a review.