deciding between two diamonds

[belle]

a stone that matches your budget and looks good

i think the homework has paid off!

 

[ilovemygirlfriend]

thank you Belle

 

[Regular Guy]

Date: 5/9/2005 5:12

9 PM
Author: ilovemygirlfriend
Heres the ideal scope images. I realize they arent flawless, but Id like to hear some input, .....

 

[Rhino]

Date: 5/7/2005 1:43:22 AM
Author: jigri2003

Date: 5/6/2005 7:39:15 PM
Author: Garry H (Cut Nut)

Date: 5/6/2005 6:20:11 PM
Author: Rhino
Just be careful with HCA scores of uncer 1.0. Our experience has been that they perform well in direct light conditions but not as well in diffuse light conditions. As I''m researching GIA''s new cut grade system (tutorial to come), technologies like red reflectors and the HCA are not accurate for determining the metric of *brightness* as they are grading it.

Welcome back from your adventures with the Super Heros Rhino.

Just a little refresher course.

HCA 1 can be a diamond that is slightly shallow, deep, steep and all sorts of things. It is impossible to generalise on the appearance.
Look at the chart for say 57% table and you will see the crown can be anywhere from 28 degrees to 38, pavilion can be 39.5 to 42. Of course there are very specific combinations for each of those angles based on the strict laws of physics.

It would be good to see the ideal-scope photo''s of the candidates

Sorry to hijack someone else''s decision thread, but what''s this about HCAs under 1 performing poorly in diffuse light conditions?

I''m in the process of buying a stone that hit 4 ex and 0.5 on the HCA, seemed to have pretty decent coverage when looked at through IS, not perfect H&A but really good arrows through the viewer, is an AGS Ideal cut, and seemed to be a good performer through my beginner eyes, even when I tried blocking light sources (hands around it, held under a table). The only issue I was unsure about was that I was somewhat concerned it might have just a few too many dark areas, but I put that down to potentially not having seen as much contrast with prior stones viewed. Now I''m a little worried that it may be the phenomenon you describe, Rhino? Any input on this, Gary?

Just catching up on a little reading after my bit in the hospital today. After thorougly studying GIA''s new cut grade system and examples they use that distinguish between their Ideal Grade 1''s and then to Grade 2''s they happen to be in agreement with my assessment about what I term the "shallow/shallow" combo''s (ie. certain stones that HCA scores under 1.0). I''m just about completing an in depth analysis of the new GIA system and how it compares to HCA, MSU, Brilliancescope, Isee2 and red reflector technology which should be all finished this week. It''s a lot of work but will be well worth the read.

Gary and I have our minor differences of opinion regarding certain issues but for the most part we are in general agreement on most. I''m not saying to *reject* a diamond that is an HCA of 1 or under, I''m just saying proceed with caution. There have been many diamonds we''ve turned down that had HCA scores of 1 and better. If you''re interested in seeing and learning why drop me a pm and I''ll forward you links that''ll help educate and also how this information correllates with GIA''s new cut grading system. One thing you must keep in mind is that the HCA is one man''s perspective of how he interprets red reflector images. Gary is far more experienced than most users of the product but there does exist differences of opinion, one of which is GIA. Before I make any judgement call however I prefer to hear both sides and of course a live inspection compared with others.

 

[Rhino]

Date: 5/7/2005 7:57:45 AM
Author: Garry H (Cut Nut)
Dont let a litle debate between Rhino and me confuse you.

HCA is a rejection tool - it is not rejecting anything. Rhino and I are good mates (in the Aussie sense that is) - we banter and carry on - but it is all good natured stuff. we just happen to be doing it at yourr party

The stone seems to be a great find. (But personally the H&A''s thing is a story - not a fact of life.)

I''d reiterate Gary''s sentiments as well. Even if it was slightly on the shallow side (which it may indeed not be) you''d still have a stone that outperforms most others.

Peace,

 

[Jimbo34]

Ideal scope images...............do they really mean that much? When you hold up your diamond ring for somebody to look at it, do those images pop in front of their face?

I would think most times the thing that catches the people eyes is how brillant and shiny it is and how it almost glows, and you should be able to tell that from what color, clarity and how well cut the diamond is. Are those pictures really necessary in buying a good diamond?

Jimbo34

 

[Rhino]

Date: 5/7/2005 11:59:36 AM
Author: jigri2003

Date: 5/7/2005 11:17:43 AM
Author: icemyster
I am not Rhino, but I work for him and sit next to him everyday...so I a privy to his great wealth of knowlege on a daily basis. I will say from personal experiane that I have intentially mixed stones that had good bscope and good ISEE2 results with stone that have great bscope and low ISEE2 results, on a tray, in no particular order, at the counter for customers in our store. In about 90% of the cases, stones that were lacking on the ISEE2, even despite outstanding bscope results, were rejected by my customers as a matter of straight choice, and before they saw any analysis on the stones.

I spoke with other people here and they have had the same experiance at the counter....a balance between brilliance scope and ISEE2 is something we definatly like to see.

Once again all apologies to ILMGF for interjecting this, but now I gotta know...

Ice, in your experiences, would the combo of 34.2 crown and 40.4 pavilion tend to qualify as the kind of stone that produces the low Isee2 scores you reference (60 depth, 56 table)? Is there some other way to test for this beside straight measurement by ISee2?

Icemyster may not be reading this now till tomorrow jiogri since we are closed today. If it''s ok I''ll answer your question. 34.2 crown with a 40.4 pavilion I would steer clear of. Unfortunately HCA and IdealScope (or any red reflector technology for that matter) can not determine the metric for *brightness* as GIA will be grading it.

 

[Rhino]

Date: 5/9/2005 7:44:49 PM
Author: Jimbo34
Ideal scope images...............do they really mean that much? When you hold up your diamond ring for somebody to look at it, do those images pop in front of their face?

I would think most times the thing that catches the people eyes is how brillant and shiny it is and how it almost glows, and you should be able to tell that from what color, clarity and how well cut the diamond is. Are those pictures really necessary in buying a good diamond?

Jimbo34

Yes Jimbo. Your general red reflectors (including IdealScope, FireScope and SymmetryScope) show a layman/gemologist whether facets are functioning as either mirrors or windows and is a great tool for assessing how diamonds will appear in direct light conditions and to a little lesser extent diffuse light conditions. In the hands of a trained gemologist can be quite an invaluable tool.

Insofar as the pattern is concerned ... YES you can observe the perfection of symmetry within H&A diamonds in various light conditions. One that is perhaps the easiest is in white hemisphere lighting which is best represented by typical cloudy day conditions. Here is a picture taken in those conditions which emphasize my point.

Hope this helps.

 

[Garry H (Cut Nut)]

Your girlfriend is gonna love that stone!

And it will blow away her friends

 

[hoorray]

Great choice! This stone will blow away every other one she sees if most of them are mall stones. You just won''t believe the difference!