Question on cut

[rock newbie]

Since the GIA report does not have the crown and pavillion angles, how can I determine if a stone has an excellent cut? I've seen the 'ideal' and 'very good' ranges for the table and depth. However, being in the range does not necessarily mean a stone has an excellent cut. Is there a rule of thumb? I know I can have it appraised before making the purchase. Is there a quicker way to make the determination?

 

[ChetLaura]

You will have to contact the vendor that has the stone and ask them to e-mail you the sarin report on that diamond. The vendors are very quick to send the sarin reports to you, and they are detailed with all of the information.

Hope that this helps.

 

[Ceillie]

I am having the same problem. I have chosen a jeweler in the area to get my setting from. I like the idea of having the brick and mortar to return to if there are ever problems with the setting. I have asked her to get a couple of stones in to look at, and here is my dilemma. She is a big proponent of the GIA certs, she even brought them up to me before I asked any questions regarding cut. She holds that the GIA is foremost in the industry. But the GIA certs do not have the crown and Pavilion info on them.


I have been frequenting the Good Old Gold site, and Jonathan seems to prefer the AGS certs because of the “range” that it allows for diamond cut grading. I have been all through his pages on Cut... I have also looked at the Pricescope cut analyzer - and the fact that Pricescope HAS a cut analyzer says they they also subscribe in the “range” theory. Here is. Now here is where the confusion lies...


Pricescope seems to indicate that it is the GIA that believes in the Range of cuts, and that the AGS is strict one to one grading... “Two years ago, the GIA released the first part of its diamond study, which challenged the long-held notion that a single set of "Ideal" proportions delivers the most dynamic diamond. Instead, they found that varying the crown and pavilion angles and table percentage resulted in a range of very brilliant diamonds. Peter Yantzer, the Director of the AGS lab, says that if the GIA finds that there are indeed multiple sets of Ideal proportions, the AGS would consider revising its system for grading the proportions for round diamonds.” (from https://www.pricescope.com/tutor_ideal.asp)

So which is it? And if the GIA is into the notion that you can vary the crown and pavilion angles - why don’t they list them? And if AGS has not changed their standards, what is the stuff that Good Old Gold is teaching? The information seems conflicting to me.

Which Cert is better? What should I be asking my jeweler to get in for me? She did not seem to think that the crown and Pavilion angles were all that important, based on the GIA Cert.

Help

 

[oldminer]

At www.gemappraisers.com you will find information about what makes a well cut diamond, round or fancy shape. In rounds, we also now use the Holloway Ideal-Scope which sometimes also determines when a diamond of unusual cut parameters also happens to act as if it was also an ideal cut. We report this occurence to our clients.

We even sell the Ideal-Scope so we are confident that it can even be used properly by a novice.

In fancy shaped diamonds there is more than light return and scintillation. Outline and length to width ratios come into play in a subjective aesthetic way. We are able to select ideal and near ideal cuts in fancy shapes, but would not expect the general public to be able to do this as readily as with round diamonds. That's why we have an interesting niche carved out for us in the world of diamonds and diamond grading.

Sarin reports are part of our regular service.