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Hca & Aga/naja Cut Class ??


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is it possible to say me that 100% or how many percent can be trust to Holloway Cut Adviser &


AGA/NAJA Cut Class Diamond Grading resuls or scores for normal people that consider to


buy loose diamond regarding Cut , Fire , Light Return ,........ RESULTS ?????

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As you know , when enter Depth & Table % , Crown & Pavilion angles in HCA , it will give you Total Visual Performance number such as 0.6 or 4.40 ,.... that are calculated based on some factors such as light return , fire , spread ,... , So , my question , if total number is 0.5 or 4.5 , what is the meaning ? is it true 0.5 more better than 4.50 or not ? is it possible some times mistake in calculation happen or not ?



IN AGA , after enter Dimension, Table, Gridle ,..... , it will calculate AGA Cut Class , Total Grade For Ex : 1 A , 3 B ..... , let to know that 1A is Good / Excellent / Ideal Cut ? or some times mistakes happen in calculation ?

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There are no mistakes; a computer makes a pretty easy calculation and it's very unlikely that the programmer got the calculation code wrong - certainly not after more than 10 years of continuous use on the web.


The problem is what does the score tell you and where it comes from. The AGA cut classes are frankly rather crude and anecdotal - it is not difficult to find great looking diamonds that are IB or IIA. For the HCA, there is some interesting research than 10 years ago was at the forefront of diamond cut research; it is now made obsolete by more sophisticated and accurate cut grading methods - first and foremost the AGS and GIA cut grades.


Most of all, bear in mind than neither the HCA nor the AGA cut classes were ever meant to be methods for selecting a well cut stone - just methods for rejecting a poorly cut one.


Is a low score on the HCA "better" than a higher one? Not necessarily. Scores are personal evaluations, and to a large extent reflect personal preferences of Garry Holloway and others that developed the HCA; also, Holloway himself says that for scores below 2 there is no relationship between score and "beauty" (and I would add in to that remark quite a few stones that score 3 or 4).


The HCA's methodology and development are described in detail here: http://www.diamond-cut.com.au/

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