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- Apr 30, 2005
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- 33,335
Wow! This was very surprising!
Isn't Mege a PS sponsor?
Isn't Garry Holloway part owner of PS?
https://www.leonmege.com/articles/item/277-hca
HCA score to trap consumers
Summary
- Not recognized by any gemological lab in the world
- Not used by professionals in the trade
- Not supported by any scientific research
- Obscure and unknown to most professionals
- Deceptive marketing tool
- Promoted by self-proclaimed diamond “experts,” who are, in reality, operatives of the “pay-per-referral” scheme
- The score is skewed towards an arbitrarily picked range of preferences
- Misleading - does not reflect the stone’s actual appearance or beauty
- The disclaimer renders the results meaningless
Among all the gimmicks designed to promote proprietary standards in diamond grading, nothing is more sinister than the infamous HCA calculator. A close cousin of the Magic 8 Ball, this is a marketing tool that is supposed to calculate a round diamond grade based on just few parameters.
Using truncated metrics in diamond evaluation is akin to deciding a beauty pageant without seeing the actual contestants, but using their measurements instead. Measurements are important, but even Donald Trump would be dumbfounded if asked to judge such a contest.
That’s why jewelry professionals don’t take HCA seriously. As a matter of fact, most of us are completely oblivious to the fact that it even exists.
Move over Mr. Trump, here comes Gary Holloway hailing from the land of Skippy the Bush Kangaroo. An online calculator that can tell which diamond is beautiful and which one is not is created.
While Louvre and Hermitage are still waiting for Gary to build a robot that is able to decide which Leonardo painting should be displayed and which one should be tossed into a dumpster, Mr. Holloway is busy selling diamonds with his own stamp of approval.
In order to get an HCA score of a diamond, you need to copy values from the diamond report, such as total depth, table, crown depth or angle, pavilion depth or angle, and the culet size.
The results are displayed in a form with a score, the lowest being the best. There is no explanation on how such whimsical properties as fire or scintillation could possibly be quantified (let’s leave this mystery unsolved for a now). There is also a “factor” called “Spread”. The difference in diameter between a “Good” and “Very Good” spread on a one carat stone is a meager 0.1 mm - the thickness of a sheet of a paper.
Looking at the chart above, one might be thrilled to find an extremely rare stone. Oops, here is the same stone with a 60% table. Same excellent grade across the board. The psychedelic chart on the right changed it’s shape (what is it? what voodoo science does it represent?) to leave no doubt in our mind that behind the scene some important calculations were actually performed.
Let’s look at a stone with a significantly lower score but fairly reasonable proportions:
Now we changed the crown angle to an extremely steep 40° and depth to a ridiculous 66%. The score increased to 4.3 from a low 5.3!!!!!!! What the @#$% ? The 40.5 degree pavilion angle improves the score even when the rest of the metrics are way out of normal range.
No wonder the following disclaimer is displayed with every result: “Even though HCA grades cut more effectively than systems like the AGS, it does not yet factor in symmetry and minor facets. Having found a diamond that scores well, you should employ an expert appraiser to examine the stone. If you decide not to, then at least compare the diamond to others and/or view it through an ideal-scope.”
Translation: “Congratulations! You just performed the incomprehensible task of calculating a meaningless number. In case anyone questions it, you are on your own. Now that you are confused and disoriented, we expect you to buy from us because we are the only ones to possess the secret knowledge of what that number actually stands for.”
Infinite bull$^#@!&*^
The HCA calculation doesn’t take into account factors such as symmetry or minor facet variation. The calculation is based on arbitrarily decided preferred parameters and any deviation will be punished by a poor score with complete disregard to overall proportions and appearance.
HCA is a lobotomized version of a GIA evaluation calculator that is available only to trade members. The GIA score does account for symmetry, polish, and minor facet data. And what’s more important, the GIA score is not presented as a verdict but as a mere advisory.
Last point to make - all diamonds are three dimensional objects observed at many different
Isn't Mege a PS sponsor?
Isn't Garry Holloway part owner of PS?
https://www.leonmege.com/articles/item/277-hca
HCA score to trap consumers
Summary
- Not recognized by any gemological lab in the world
- Not used by professionals in the trade
- Not supported by any scientific research
- Obscure and unknown to most professionals
- Deceptive marketing tool
- Promoted by self-proclaimed diamond “experts,” who are, in reality, operatives of the “pay-per-referral” scheme
- The score is skewed towards an arbitrarily picked range of preferences
- Misleading - does not reflect the stone’s actual appearance or beauty
- The disclaimer renders the results meaningless
Among all the gimmicks designed to promote proprietary standards in diamond grading, nothing is more sinister than the infamous HCA calculator. A close cousin of the Magic 8 Ball, this is a marketing tool that is supposed to calculate a round diamond grade based on just few parameters.
Using truncated metrics in diamond evaluation is akin to deciding a beauty pageant without seeing the actual contestants, but using their measurements instead. Measurements are important, but even Donald Trump would be dumbfounded if asked to judge such a contest.
That’s why jewelry professionals don’t take HCA seriously. As a matter of fact, most of us are completely oblivious to the fact that it even exists.
Move over Mr. Trump, here comes Gary Holloway hailing from the land of Skippy the Bush Kangaroo. An online calculator that can tell which diamond is beautiful and which one is not is created.
While Louvre and Hermitage are still waiting for Gary to build a robot that is able to decide which Leonardo painting should be displayed and which one should be tossed into a dumpster, Mr. Holloway is busy selling diamonds with his own stamp of approval.
In order to get an HCA score of a diamond, you need to copy values from the diamond report, such as total depth, table, crown depth or angle, pavilion depth or angle, and the culet size.
The results are displayed in a form with a score, the lowest being the best. There is no explanation on how such whimsical properties as fire or scintillation could possibly be quantified (let’s leave this mystery unsolved for a now). There is also a “factor” called “Spread”. The difference in diameter between a “Good” and “Very Good” spread on a one carat stone is a meager 0.1 mm - the thickness of a sheet of a paper.
Looking at the chart above, one might be thrilled to find an extremely rare stone. Oops, here is the same stone with a 60% table. Same excellent grade across the board. The psychedelic chart on the right changed it’s shape (what is it? what voodoo science does it represent?) to leave no doubt in our mind that behind the scene some important calculations were actually performed.
Let’s look at a stone with a significantly lower score but fairly reasonable proportions:
Now we changed the crown angle to an extremely steep 40° and depth to a ridiculous 66%. The score increased to 4.3 from a low 5.3!!!!!!! What the @#$% ? The 40.5 degree pavilion angle improves the score even when the rest of the metrics are way out of normal range.
No wonder the following disclaimer is displayed with every result: “Even though HCA grades cut more effectively than systems like the AGS, it does not yet factor in symmetry and minor facets. Having found a diamond that scores well, you should employ an expert appraiser to examine the stone. If you decide not to, then at least compare the diamond to others and/or view it through an ideal-scope.”
Translation: “Congratulations! You just performed the incomprehensible task of calculating a meaningless number. In case anyone questions it, you are on your own. Now that you are confused and disoriented, we expect you to buy from us because we are the only ones to possess the secret knowledge of what that number actually stands for.”
Infinite bull$^#@!&*^
The HCA calculation doesn’t take into account factors such as symmetry or minor facet variation. The calculation is based on arbitrarily decided preferred parameters and any deviation will be punished by a poor score with complete disregard to overall proportions and appearance.
HCA is a lobotomized version of a GIA evaluation calculator that is available only to trade members. The GIA score does account for symmetry, polish, and minor facet data. And what’s more important, the GIA score is not presented as a verdict but as a mere advisory.
Last point to make - all diamonds are three dimensional objects observed at many different