Difference between ideal cut and vendor superior cut?

[denverappraiser]

Date: 9/17/2008 11:55:49 AM
Author: GCAL
That brings me to my conclusion, that GCAL is the only laboratory in the world, that has a fully backed guaranteed certificate for the accuracy of the 4 C's...

Hi Angelo,

Welcome to the forum.

Although it appears routinely in your advertising, I think you’ll find the above statement is not correct, and hasn’t been for many years, if ever.

For example, here are two labs, both of which have representatives who are regular contributors here, that have a very similar guarantee to your own where if a stone is submitted to GIA as an arbiter and the grading doesn’t match within a certain range then the client will be eligible for damages.

Sarasota Gemological Laboratory

Accredited Gem Appraisers

I'm sure there are others as well.

The difficulty with understanding your light performance grading system is the ‘black box’ of your proprietary software. Since this is a closed system, it is, at best, only possible to use it to compare GCAL graded stones with other GCAL grades stones. It is impossible to say whether a particular stone is better, worse or even similar to an alternative stone graded by another lab. The data is not available and even if it were, the formula for producing the scores is proprietary. That may be ok if people use it for what it is but it renders the system useless for the purpose being asked in this thread, namely how to compare a GIA ‘ideal’ (which I take to mean GIA-excellent) with a BN/GCAL ‘signature ideal’ based purely on the information and images provided in the various reports.

This leaves with only the question of whether the score provides useful information for customers comparing one GCAL graded stone against another. Is a light performance of 30 twice as good as a light performance of 25 or is it 1% better? Better in what way? Is the scale even linear? How can a shopper compare two stones with different scores and different images without knowing what has been measured and how the scores and images relate to those measurements? Since what is being measured is itself a secret, this seems impossible to answer in a meaningful way. As with the above, if we don’t have a scale or some way of interpreting the results provided, this is no more helpful than when a car dealer describes something as a ‘creampuff’. Maybe it's a fantastic car, but what has really been learned by that description?

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[WinkHPD]

Post withdrawn, I thought I was welcoming Don Palmieri to Pricescope, but later realized it was Angelo, who I am thinking may be his brother or other relative.

I have known Don for many years and wanted to welcome him to Wonderland.

Wink

 

[Garry H (Cut Nut)]

Date: 9/28/2008 6:00:02 PM
Author: Wink
Post withdrawn, I thought I was welcoming Don Palmieri to Pricescope, but later realized it was Angelo, who I am thinking may be his brother or other relative.

I have known Don for many years and wanted to welcome him to Wonderland.

Wink

Wink no damage done,
Angelo is Don''s very able Son, and I am sure they will both have understood and welcomed your welcome.