BScope on EC

[chrono]

I am new to learning about diamonds especially Cut. Most of the information is about RBs though, so I am hoping that the experts of PS will be able to educate me on ECs. There is so little information on the internet on fancies.

I know that ECs are step cut and will never be brilliant like the RBs. That said, what should I look for when physically viewing an EC? Fire? Big bold white flashes?

What is the best possible result an "ideal" EC should score on a BScope in all 3 categories of brilliance, dispersion and scintilation?

How much difference will I see when comparing a 1A vs 1B vs 2A vs 2B cut side by side?

 

[chrono]

No replies yet? Am I posting this in the correct forum?

 

[valeria101]

No... no wrong forum. The Q is not very easy I am affraid.

If you are asking what is the relation between AGA classes and Iscope readings on step cuts, the answer is just not there. The AGA parameters are quite tight so assuming the stones you are considering do not have very unusual faceting (I remember some with huge, steep facets on the pavilion, for example) they should be close brothers.

Since no rule ties down the index of those "steps" - there is no way to precisely link proportions to light return in this case, like the HCA does for rounds. Sure there is some "normal" cut model, but from saying this to an absolute guarantee good for "shopping by nimbers" is some distance.

Anyway, the latest version of the GemAdviser produces light return reports for fancy shapes. It's fun to play with and there are a couple of intriguing examples too.

No hard rules for the Iscope either... for better or worse, and I would rather not use Bscope scales to judge wether an Iscope reading belongs to a good, bad or ugly piece. The relation is there, but doesn't seem completely straightforward. Some simple rule such as "the redder the better" cannot do much harm, but, as you saw yourself, there is no receipe for "splitting hairs" of cut quality for step cuts yet. My opinion? That's great!

 

[valeria101]

This is the type of report I was talking about. If I remember right, Jonathan mentioned that the scale is not shape-specific - so the rank obtained compares your stone with any other stone, be it H&A round or marquize that receives such a report.


Step cuts being my favorite, I hope this thread gets very long