Colour grading

[flyingharp]

OK this is one for the pros...

Is colour grading all done on Gran Calorimeters these days? Or do they still rely on daylight tubes, calibrated stones and white cards? (Or perhaps only at noon, as they do in the CSO...)

I guess this question relates more to original certification, whereas I can see that the calorimeter would be of great time-saving benefit at the retail end...)

 

[valeria101]

'Calorimeter' might measure temperature and a 'Colorimeter' might get diamond color grades. The rest sounds like... Astrology ?!

 

[flyingharp]

----------------
On 10/21/2003 3:19:50 PM valeria101 wrote:

'Calorimeter' might measure temperature and a 'Colorimeter' might get diamond color grades. The rest sounds like... Astrology ?!----------------

Hee hee! I stand corrected!

Astrology... but don't folk go diamond shopping when the moon turns blue...

 

[mike04456]

I don't know anyone who uses a Calorimeter. Where I come from, it's still being done with a Mark 1 Eyeball and a set of masterstones./idealbb/images/smilies/naughty.gif




There are some high-tech toys that can determine a color grade but they have not gained widespread acceptance yet. Even with all the technical assistance in the world, people are still going to want to evaluate a diamond with their eyes.

 

[pqcollectibles]

I know of a Gemologist in Atlanta that uses both Master diamonds and a Gran Colorimeter. He eyeball's diamonds with his Masters and confirms the color grade with the Colorimeter. He even gives the diamond buyer a nice little "Colorimeter" report verifying the color grade.

 

[smaggard]

When I had my stone sent to RockDoc, he uses both the GIA master set as well as the colorimeter.
The GIA cert said G color, and with the master set he also agreed G, however the colorimeter graded it a lower F.
Rockdoc states also in his report that he has found the colorimeter to be more accurate at colors below H, so I,J,K etc see more accuracy than the higher color stones.

 

[aljdewey]

Hasn't Rhino posted pics of colorimeter readings on some of his stones?

 

[smaggard]

This was the output FYI, and what the Gran prints out at the bottom.