Validity of HCA

[slmulkey]

I have been shopping for diamonds and received the following response when I ask for the pavillion and crown angles:

"I would not rely to heavily on the HCA it is not recognized by
GIA and AGS and does not give a true brilliance indication. Try putting in several parameters of some know excellent cut diamonds and some will
have a good rating and some will not."

Is this a common opinion in the industry, or is this guy just trying to sell me a diamond?

By the way, I still plan on using the HCA, I figure its better to be safe than sorry, especially since I won't see the diamond until I've already paid for it

 

[Greentree]

It will be difficult to find diamonds with very low HCA scores so rather than embarking on an endless search for the diamond that scores 0.4, use the HCA to distinguish between well cut and poorly cut and to decide if the asking price is fair. The whole idea behind the HCA is to help you make an informed purchase. That is, don't use it as some sort of microscopic inspection tool, use it as a guide.

 

[Mara]

I too had the same thought/question, and received an answer that I thought covered all the bases. Basically, what I am going to do is look for an AGS Triple Ideal scored diamond, since the certificate already has the crown & pav angles on it, and then see what it scores on the HCA. If it's under 2, and thats acceptable to me (actually I'm being very picky and going under 1.0), and I've got the AGS Triple Ideal certification and it's the color and quality and price that I am looking for, it sounds good to me! That way I know I have my bases covered, the certificate says it got a good grading from AGS, and the strict HCA says good too. Especially for online purchasing, since I will not see my diamond before purchasing, this is key for my peace of mind.

I too have run a few diamonds through the HCA that got Triple Ideal AGS certs and a few that are H&A cuts marked up with a premium price, and they came up as 2.4-2.6 which wasn't super impressive to me. So I knocked them out of the running. There are too many other potentials out there that are reasonably priced for me to waste my time wondering and hemming and hawing over one that is already questionable.

In the end it's more about peace of mind, but I read many of the details on how the HCA was created and all the intelligence that was used, and personally I feel it's a much better judge of a diamonds 'character' than my local jeweler who just wants to sell me a stone. Just my opinion.

Good luck!
Mara

 

[rsilvers]

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"I would not rely to heavily on the HCA it is not recognized by
GIA and AGS and does not give a true brilliance indication. Try putting in several parameters of some know excellent cut diamonds and some will
have a good rating and some will not."


"Known" excellent cuts in what way? Known because AGS says so? If a stone is AGS0 and get a poor HCA score I would not buy it. If a stone gets a great HCA score but is not an AGS0, I would consider it a bargain.

That being said, I have not reviewed the code and theory of HCA and cannot say forst hand that it is good, but I trust it FAR more than what anyone in a jewelry store says about it. Certainly that dealer's comment did not disprove the validity of HCA.

 

[student]

One thing I've noticed using the HCA is that it is hard to find a stone that gets four excellents, but it is fairly easy to find stones that get excellents in everything but spread. Since there are more of the latter type of stone, you can probably shop around and get a good deal on a slightly heavier stone of this sort that will look the same and be as much or cheaper than one that is a bit lighter but with excellent spread.

That is to say, a low price per carat can be a substitute for excellent spread, and may be easier to find.

As a consumer, I have found it difficult to arrive at confident judgements about the usefulness of the HCA and other tools such as ideal-scope images and Brilliancescope scores to make judgements about diamonds. Each has its advocates and its critics, and all offer plausible arguments that I don't think a non-expert could really poke a hole in. (You will see some obviously bad arguments out there as well, however.)

That said, these arguments tend to point out particular problems with the various tests, rather than undermining their usefulness altogether. And some of the arguments are about whether the tests give bad results for good diamonds. This is important to dealers who want to sell diamonds, but not so important for consumers who want to buy them. We consumers would only be more worried about the tests giving good results for bad diamonds. If we pass over a beauty that's no big deal, so long as we get a good diamond in the end. Notice that your dealer focused on the HCA giving bad results for good diamonds, and not vice versa.

I figure that I have a good shot at getting a top-of-the-line diamond if I get one that yields excellent results on at least two of the three tests--ideally on all three. But I still do get that lamb in a lions' den feeling every now and then!

Any more comments from the experts?