Gemex v. Megascope? Technical question.

[mercoledi]

In this one.

Looking through all of the documents GOG makes available, I noticed that the megascope OGI FireFrace shows Ideal Brilliance, Ex/Ideal Fire and Ideal Scintillation. The Gemex report shows maxed out Very High Brilliance and Fire, but Very High Scintillation.

Are the differences described significant in the context of the diamond''s performance? What causes the discrepancy between the two systems? If they both measure light return, do they use different light sources?

Thanks!

 

[Ellen]

Merc, I''m going to leave this answer to a real pro, but will give you a bump in the hopes it will help one see it!

 

[whatmeworry]

Gemex get direct readings of the actual diamond and gives it scores for Brilliance, Fire, Scint. The OGI FireTrace (Megascope) measures the diamond and then predicts the light performance. So yes, different light sources (real and modeled). Even though they are trying to measure are the same in name (brilliance, fire, sparkle/scint), what they are really measuring technically are different animals. So you should expect differences between them. As to whether the differences between the systems are significant, I don''t know. I suspect not. Gorgeous diamond though.

 

[mercoledi]

So the Gemex is a real reading and the FireTrace is modeled? Cool. Can the FireTrace model for any stone, i.e. for older cuts could you enter the measurements of the stone and predict brilliance/fire/scintillation?

 

[John P]

Beautiful diamond.

Date: 7/22/2008 3:40:32 PM
Author: mercoledi
So the Gemex is a real reading and the FireTrace is modeled? Cool. Can the FireTrace model for any stone, i.e. for older cuts could you enter the measurements of the stone and predict brilliance/fire/scintillation?

No. One would need a full 3D scan of the diamond - not basic measurements - for a proper ray-trace. The OGI metric is not scientifically vetted so it's unclear what that machine is actually measuring. It would be more meaningful to run a 3D scan through the AGS Proprietary Grading Software (which your seller has, I believe) since that system is scientifically vetted. It provides meaningful values for brightness, dispersion, contrast and leakage.

The attempt to evaluate scintillation in either of these metrics is highly debatable. Your seller is better equipped to give you guidance than those "measures" in my opinion. Here is some recent discussion about Gemex: https://www.pricescope.com/community/threads/brilliancescope-revisited.89969/

 

[mercoledi]

Date: 7/22/2008 3:56:00 PM
Author: John Pollard
Beautiful diamond.
The OGI metric is not scientifically vetted so it''s unclear what that machine is actually measuring.

The attempt to evaluate scintillation in either of these metrics is highly debatable. Your seller is better equipped to give you guidance than those ''measures'' in my opinion. Here is some recent discussion about Gemex: https://www.pricescope.com/community/threads/brilliancescope-revisited.89969/

Thanks Jon, are you settled back into the real world yet?

Is a 3D scan the Sarin? So if I had a Sarin and a Gemex program, I could predict (sort of) b/f/s.

Is the OGI Fire Trace at all reliable, or just a general predictor? If it isn''t based on scientific measurements and predictive algorithms, what is it based on? I can''t say I find that particularly reassuring or informative as a measure or performance. I work with predictive algorithms myself and even the ones trained on large, bio-relevant data sets aren''t great.

I''m not considering this diamond, I just ran across it in another thread and was intrigued, I don''t think I''ve seen both OGI and Gemex listed for the same stone before.

Thanks for the great info as always!

 

[John P]

Date: 7/22/2008 8:00:40 PM
Author: mercoledi

Date: 7/22/2008 3:56:00 PM
Author: John Pollard
Beautiful diamond.
The OGI metric is not scientifically vetted so it''s unclear what that machine is actually measuring.

The attempt to evaluate scintillation in either of these metrics is highly debatable. Your seller is better equipped to give you guidance than those ''measures'' in my opinion. Here is some recent discussion about Gemex: https://www.pricescope.com/community/threads/brilliancescope-revisited.89969/

Thanks Jon, are you settled back into the real world yet?

Is a 3D scan the Sarin? So if I had a Sarin and a Gemex program, I could predict (sort of) b/f/s.

Is the OGI Fire Trace at all reliable, or just a general predictor? If it isn''t based on scientific measurements and predictive algorithms, what is it based on? I can''t say I find that particularly reassuring or informative as a measure or performance. I work with predictive algorithms myself and even the ones trained on large, bio-relevant data sets aren''t great.

I''m not considering this diamond, I just ran across it in another thread and was intrigued, I don''t think I''ve seen both OGI and Gemex listed for the same stone before.

Thanks for the great info as always!

Hi Mercoledi,

Part of me is still on a sunny beach, but it''s less and less each day (sigh). The Sarin machine performs a 3D scan. So does OGI. So does Helium. I am sure the FireTrace is based on the 3D scan the OGI took, but those scores are based on whatever OGI decided to use as a metric (I would presume it''s a predictive calculation, similar to HCA, but I am guessing). In any event I don''t know that there is any science behind it. At the same time, it''s always interesting to get abundant data and see how it correlates. Cheers.