Cut Grade vs Holloway Cut Adviser

[Jcm412]

What is the difference between a normal cut grade by say GIA vs the Holloway Cut Adviser (HCA)? I don't understand how there can be a excellent cut grade by GIA then only a good rating by the HCA and then you can have a good GIA rating with a excellent HCA rating. How can the be so different? Which is better to go by?

 

[John P]

What is the difference between a normal cut grade by say GIA vs the Holloway Cut Adviser (HCA)? I don't understand how there can be a excellent cut grade by GIA then only a good rating by the HCA and then you can have a good GIA rating with a excellent HCA rating.

I can identify at least three discernible levels in GIA's "EX" cut grade, and more if you want to include technical craftsmanship as a valuation-component.

How can the be so different? Which is better to go by?

It all depends. How picky are you? How visually acute are you? How "married" to today's GIA cut grades are you, versus future value as cut grading evolves? ...Statistically a GIA "EX" diamond is better than 65-70% of other commonly produced round brilliants. Whether it's in the 66th or 99th percentile depends on many factors.

The Pricescope contributors can assist to a large degree in identifying how "Excellent" a given diamond is if you provide more information.

 

[Christina...]

The hca is a tool used to narrow down a long list of potential candidates into a much smaller more manageable list of contenders that are worth a closer look. Hca is a good starting point, but it wasn't designed to make selections, only to eliminate them. It can only tell you how a stone will likely perform based on four proportions that have been averaged and rounded by GIA. When trying to determine a stones likely light performance an idealscope image will produce much more meaningful and accurate information. The HCA will on occasion allow a beauty to slip away or a dog to end up on your short list, but it does its job very well if used for its intended purpose.

To be more specific as to how a GIA EX can score poorly it would be helpful to use an example. I assume you ask the question because you are considering a stone that received an excellent cut grade but scored poorly? If you'd like to post the proportions we can explain how and why it can happen. In general though GIA has a much broader range of proportions in their EX cut class, many feel its too broad and includes under performing stones. they also exclude certain proportions that labs such as AGS consider candidates for their ideal cut grade and which score very well on hca and in reflector images.

 

[Jcm412]

I don't know if it scored poorly but not great.
http://www.b2cjewels.com/Certificate.aspx?StockNo=3300345

 

[TC1987]

What is the difference between a normal cut grade by say GIA vs the Holloway Cut Adviser (HCA)? I don't understand how there can be a excellent cut grade by GIA then only a good rating by the HCA and then you can have a good GIA rating with a excellent HCA rating. How can the be so different? Which is better to go by?

Different systems, because the GIA developed one system, and the Gary Holloway developed the HCA, and they didn't necessarily agree on everything nor work in tandem, ever. AGS has another system, and then the AGA/NAGA system is yet another ratings system. EGL probably has its own, too. The cut ratings systems and tools were developed as a classification system to put labels on diamonds, and at least some of the systems and evaluation tools were developed with the aim of making long-distance diamond buying feasible and easier.

Which is Better: I still gravitate toward diamonds with AGS reports vs. GIA. Cutters and vendors shop the labs to get the best rating for any given diamond. The GIA has a broader range of "excellent" than AGS does, so only the best cut are going to get sent to ASG to begin with. I'd say if the HCA score is 2 or less and the diamond is also GIA excellent, then it's a candidate. But diamonds vary, and you can have two diamonds with almost the same specifications on paper, but they do not look or perform exactly the same when you see them side by side.

 

[sakari_8]

I think HCA does help in select the right stone especially when you buy online, however it is still not the perfect method,
if the stone is cloudy HCA would not lower the Score, I did check the score its 3.9 which is not bad, If you are getting
good price on the stone than I think its a good stone to consider.

 

[Christina...]

I don't know if it scored poorly but not great.
http://www.b2cjewels.com/Certificate.aspx?StockNo=3300345

If you request an idealscope I believe that B2C will provide it for you. It may be fine, but with numbers like these I wouldn't proceed without additional information.