How to interpret Diamcalc?

[echelon6]

Hi all

In gem advisor, under the Cut Quality section, there's usually scores for Light return mono, Light return stereo, Dark zone mono, which are usually around 1 for all super-ideal diamonds.

Can anyone pls tell me whether these numbers are important? i.e. should we all aim for the highest scores in all categories? I noticed that the TIC only gets around 1 for each score so I doubt maximisation is possible.

Is there a diamond with scores of 1.1+ for several categories? and is this a good thing?

Also if a diamond is nearing mid 0.90s for most of its scores, is that bad or very bad?

For me, I think I trust this software more than pixel-counting methodologies like BScope, since this is based on maths and ray tracing... I would imagine that minute numerical differences in Diamcalc actually mean something real, unlike BScope. Any comments?


EDIT:

Another question:

For each section (Light return mono / stereo / dark zone) when you click it, it shows scores for Static View and 30 degree tilt.

What is to be desired here? Stability or variance? (i.e. the TIC remains stable at around 1 between static and 30 degree, but some diamonds I've seen have 1.2 at Static, and 0.8 at 30 degrees)

 

[whatmeworry]

actually adding to your list of questions, rather than answers.

Just my observations since I can''t find documentation on the scoring, so I could be completely wrong. I believe that BLR (let''s say the score for a static view), is somehow calculating the BLR by integrating the perceived brilliance over the face of the stone. In that respect it''s not much different from pixel counting, although what DiamCalc and what BScope are counting are different. There appears to be a fixed lighting condition (fixed lights, fixed head blocking, etc) in which BLR is calculated. The scores are nomarlized so TIC = 1.0.

Your question about stability or variance is a good one. Dave Atlas will argue that stability (face up) is the most important one. Other''s will argue the other variance is better. Is it better to have an all around good performer or one that really pops in the face up view?

The one thing that is missing in DiamCalc (although Garry has said next version will include it) is fire. If you lose something in light return dropping to 0.9 instead of 1.0, do you gain in something else like fire? So in that respect getting a 0.9 by itself may not be a bad thing if you increase your fire score.

Good questions though.

 

[echelon6]

Thanks for your insight. I think I''m thinking along the same lines here in regards to variance of scores...

How about some averages from experience? I''m considering a stone with all mid90s and it seems like below average compared to most other stones I''ve seen (some have high variances, some have around high 90s to low 1.0''s etc). Not sure of what to expect for a super-ideal stone - in terms of performance as measured by Diamcalc

Any experts or anyone else care to chime in?

 

[echelon6]

bump

 

[Garry H (Cut Nut)]

For all catagories 1.00 = Tolkowsky

At this stage BLR's (basic light response) do not include any measure of fire or scintillation and the BLR's have not been thoroughly checked out with a Master Stone Study that we are working on http://www.octonus.ru/oct/mss/index.phtml here are the stones we have had cut so far. They are sitting in my tub at work while we wait for the remaing stones and a couple maore Sergey wants to add after a recent '41' discussion here on PS.

There can be problems with things like contrast for example - the mathematical formula is along the lines of the length of boundary of say a dark zone adjoing a lighter zone multiplied by a factor for the difference in intensity or drakness between the
2 zones. Human eyesight and human perception testing might result in some 'resetting' of these values.

so all in all the OctoNus GemAdviser / DiamCalc BLR information is based on a Tolkowsky with a very thin girdle - 1% at valley - from memory (not the DC default 57% stone)

 

[Serg]

Date: 7/20/2007 9:25:39 PM
Author: Garry H (Cut Nut)
For all catagories 1.00 = Tolkowsky

At this stage BLR''s (basic light response) do not include any measure of fire or scintillation and the BLR''s have not been thoroughly checked out with a Master Stone Study that we are working on http://www.octonus.ru/oct/mss/index.phtml here are the stones we have had cut so far. They are sitting in my tub at work while we wait for the remaing stones and a couple maore Sergey wants to add after a recent ''41'' discussion here on PS.

There can be problems with things like contrast for example - the mathematical formula is along the lines of the length of boundary of say a dark zone adjoing a lighter zone multiplied by a factor for the difference in intensity or drakness between the
2 zones. Human eyesight and human perception testing might result in some ''resetting'' of these values.

so all in all the OctoNus GemAdviser / DiamCalc BLR information is based on a Tolkowsky with a very thin girdle - 1% at valley - from memory (not the DC default 57% stone)

Garry,
All parameters can find here http://www.octonus.com/oct/products/3dcalc/standard/param17.phtml

 

[echelon6]

So... for the layman, 1.00 = Tolk, then <1 = inferior performance to tolk?

Would there be some sort of inverse relationship then? between Static view and 30 degree tilt? Since Tolk would score 1 in both, but if a diamond scores 1.2 in static, would it score at most 0.8 in 30 degree?

Any opinions on a stone getting mid 90s in all categories? And what about a stone that gets 1.2s and 0.8s for the static / 30 degree views?

Thanks

 

[Garry H (Cut Nut)]

the DiamCalc model is perfect in every aspect whereas there is no perfectly sym real diamond. This might account for 0.02 or 0.03 (2-3%) from my experiance.

Date: 7/22/2007 1:13:33 AM
Author: echelon6
So... for the layman, 1.00 = Tolk, then <1 = inferior performance to tolk?

Would there be some sort of inverse relationship then? between Static view and 30 degree tilt? Since Tolk would score 1 in both, but if a diamond scores 1.2 in static, would it score at most 0.8 in 30 degree?

Any opinions on a stone getting mid 90s in all categories? And what about a stone that gets 1.2s and 0.8s for the static / 30 degree views?

Thanks

The scores for tilting and face up are all standardized to 1.00 for the etalon model.

Getting mid 90''s might also get a better score for fire and dynamic scintillation (DETAS) - and you dont have that data - it will only be available in the pro version of DC3pro

 

[echelon6]

Will I be able to see such info with the free Gem Adviser software?

Thanks

 

[Garry H (Cut Nut)]

Date: 7/22/2007 9:15:12 AM
Author: echelon6
Will I be able to see such info with the free Gem Adviser software?

Thanks

Maybe one day, but not for a while