Find your diamond
Find your jewelry
shape
carat
color
clarity

GIA Research Conducts Largest-Ever Series of Observation Tests on Diamond Appearance

Status
Not open for further replies. Please create a new topic or request for this thread to be opened.

pricescope

Ideal_Rock
Joined
Dec 31, 1999
Messages
8,266
Quote:
Over the past 18 months, GIA has collected nearly 40,000 observations of more than 1,000 diamonds in a variety of controlled environments as well as in typical trade settings.
...
Retailers and consumers were also tested in various controlled and natural environments at other times throughout this phase of the research. In addition, thousands of observation tests have been conducted at GIA in controlled environments using experienced laboratory observers.
.[/u]
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,272
Hi Leonid

Actually I referenced that article in another thread. It is certainly worthy of it's own thread though. Of note is this one as well which has some intereting commentary on the minor facets and their effect on DCLR.

http://www.professionaljeweler.com/archives/articles/2002/jan02/0102dg.html

Peace,
Jonathan
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,272
I'm not going to argue. All I can say is you're going to love our page on the minor facets once it's finished. :)

Peace mate.
Rhino
 

Richard Sherwood

Ideal_Rock
Joined
Sep 25, 2002
Messages
4,924
Hey Rhino, who's that guy you got to stand in for your icon photo?

That's way too much of a tan for a New Yorker to have... All you New Yorkers are pasty white, didn't you know?

Rich, BBGG (beach bum graduate gemologist)
Sunny Sarasota Gemological Laboratory
 

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,519
----------------
On 12/20/2002 7:10:43 PM

Hi Leonid

Actually I referenced that article in another thread. It is certainly worthy of it's own thread though. Of note is this one as well which has some intereting commentary on the minor facets and their effect on DCLR.

http://www.professionaljeweler.com/archives/articles/2002/jan02/0102dg.html

Peace,
Jonathan
----------------

RE:

"..Over the past 18 months, GIA has collected nearly 40,000 observations of more than 1,000 diamonds in a variety of controlled environments as well as in typical trade settings. No cut-evaluation methodology currently used in the trade has been empirically tested in this manner...."

In order to confirm the basic theoretical "discoveries" there is no need to study more than 1,000 diamonds .
10-100 stones are enough for this goal.
Research of that size is required only in case when theoretical research are weak and practical testings are required to search information for elimination of theoretical mistakes or for creating estimation system based only on practical researches. However that research is not enough in the second case.
 

Serg

Ideal_Rock
Trade
Joined
Mar 21, 2002
Messages
2,519
----------------
On 12/23/2002 5:20:12 AM

Sergey you suggest that the GIA theory is weak?

----------------


suggest ? :) I am sure.
We and other(Michael,Marty,Garry,...,Bruce) have proved it.
 

lawmax

Brilliant_Rock
Joined
Dec 31, 1999
Messages
1,317
----------------
On 12/23/2002 5:40:01 AM


----------------
On 12/23/2002 5:20:12 AM

Sergey you suggest that the GIA theory is weak?

----------------


suggest ? :) I am sure.
We and other(Michael,Marty,Garry,...,Bruce) have proved it.

----------------


...,

Who is that?


:cheeky:
 

oldminer

Ideal_Rock
Trade
Joined
Sep 3, 2000
Messages
6,397
There is very little to be gained by testing visual appearance. Where is a scientific result going to be generated? Statistics aside, how are we going to know more?

Would it not be more decisive to test different diamonds and cutting configurations in some scientific piece of equipment that made direct and repeatable measurements of brilliancy, scintillation and fire?

How many people can tell you what makes a diamond beautiful? How many FEWER of those could tell you why one is more beautiful than another? What small minority of these folks could define what set of characterisitics creates beauty in the stones they select as the best?
Finally, of these, who can define beauty to begin with? Beauty to begin with is not science.

Will the results be flawed if the basis is so subjective as beauty? Have they taken into account such things as medium or larger culets? Has out-of-roundness been considered as a potential fault in beauty?

These are only a few of my concerns for continuing down that pathway in order to define or re-define "ideal cutting". I think there is better that can be done. My mind remains open for the results of all these tests. Maybe there will be more knowledge gained and that is welcomed. I fear all this work will not lead to a far better way to judge diamonds.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,320
Dave if you have the theoretic data then it needs to be tested by humans to see that the human best matches the theoretic.

This is to account for pscho-physiological factors.

We also need to test the limits of human ability to judge small variations in say symmetry. That way you can say "excellent" should be from .000001 to .00015, and 'very good' from .00015 to ......

A hurried explanation :)
 

Rhino

Ideal_Rock
Trade
Joined
Mar 28, 2001
Messages
6,272
Greetings ya'll,

Gary, in answer to your question I see many H&A stones with stars falling as low as 45-50% and as high as 60-65% with most falling somewher in the middle. Lower girdles as low as 75% and as high as 85%. It's a mixed bag out there and very very few (I can count them on one hand) are producing consistent results on a facet by facet basis when we consider the minor facets.

To some perhaps this may make no difference at all and from what you suggest seems to be the general consensus. I may be one who thinks differently, but that is just me and I'm fine with that. While I do have my personal preferences I do carry super ideals of many facets (pun intended). My advice every single time is COMPARE and see for yourself and choose what you like best. We have done MANY emperical tests with clients all the time. Tests that include showing them 2 stones side by side where the only differences were in the minor facets and according to my observataions THERE is a preference that people have chosen when given the opportunity. BTW, it's never a comparison of a beautiful stone vs an ugly diamond ... it's between 2 beautiful stones which they then choose a preference for.

Simple as that. As long as we're in business we'll always offer this opportunity to our clientele and let them purchase what they wish and we'll always offer both.

Peace,
Rhino
 
Status
Not open for further replies. Please create a new topic or request for this thread to be opened.
Be a part of the community It's free, join today!
    Radiant Ruby Cluster Ring
    Radiant Ruby Cluster Ring
    Recutting And Resetting A Heirloom
    Recutting And Resetting A Heirloom
    Princess Diana: Timeless Jewelry Every Woman Should Own
    Princess Diana: Timeless Jewelry Every Woman Should Own

Need Something Special?

Get a quote from multiple trusted and vetted jewelers.

Holloway Cut Advisor



Diamond Eye Candy

Click to view full-size image.
Top