cut advisor ?

[lara]

could somebody tell me now accurate an HCA score is with only the crown and pav. % rather than angle info. If the crown and pavilion % is almost useless, why does the program give the option to input that data? thanks

 

[Mara]

There have been other posts on this in the past, but here's the info again.




%'s are rounded, so they are not going to be as accurate as the angles which are spot on.




%'s still give you an idea of how the stone will perform, kind of like a 'range'...but the angles will be the true result.




I have noticed that the % results on the HCA tend to be better than when you actually plug angles in (e.g. later if you get them). For example, if the %'s give you a 2.2...if you plug angles in later....the score is more around 3 with angles. Or another example is if you have a 1.0 with the % and then the angles later could be 1.7.




In terms of the first example (2.2 to 3), the stone would be rejected by me anyway. In terms of the second stone, 1.1 or 1.7..both are still good, so the %'s would have kept you from tossing the stone until you got the angles later. So it can be helpful in weeding out duds or keeping stones that may be very good from the start.




Where it gets tricky for example is if with %'s the stone scores something like a 1.7 and then with the angles later is a 2.8. Would you still want to buy the stone if it was 2.8 on the HCA? Some would say no.




So anyhow take the %'s as useful but with a grain of salt. Try to get the angles, they are the ones that will give you the accurate result in terms of HCA.

 

[Giangi]

Welcome! Beautiful name!

As the old sayin' goes, it's better that nothing. Considering the lack of information and the misinformation that we see everyday (jeweler are inventing any possible excuse not to loose a sale), %'s are good. As always, if you ca, get the angles. But with the %'s at least you'll know, as Mara stated, the range of possible performance of the stone.

 

[lara]

thanks, giangi

 

[lmh]

oops, and thanks Mara!

 

[Garry H (Cut Nut)]

Yes thanks guys

One reason angles are better is that the measurement of pavilion angles is more accurate and generally the % depth slightly understates the angle when we calculate the angle from you % data.
It is to do with the ability to detect a very small culet and other such things.