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Color and saturation grading equipment


#1

Hi,

I would like to do measurements of color and saturation for my collection of gems.

Wich equipement do I need ? What is the price ?

Thank you
Have a nice day


#2

https://www.gemguide.com/appraisal-software/


#3

oops my bad https://www.gemguide.com/services/world-of-color/


#4

ok I see the world of color thank you

But I have another question. Is there a way to analyse the color with a electronic equipment to know precisely the hue ?

This world of color could be useful to know the color and saturation.

What kind of light do you use for this ?


#5

Ah yes the color electronic magic box the holy grail of colored stones. Seems to me one of those has been in “Beta test” many times by many companies and yet we still do not have one . ie https://www.jckonline.com/editorial-article/from-colormaster-to-gemset-to-gem-e-wizard-computer-might-be-the-answer-for-gia/ If you do find a machine that can color grade colored stones I would love to see it . Some one may have done this but i have not seen one for sale .I do not do enough grading to afford any fancy machine as for light I have a frosted glass window over my bench ya old school but again I do not do that much " grading " If i like what I see I buy it if not I send it back. Ps check out royjohns post in Quick gem ID test in our fourms.


#6

ok thank you

it seems that everything is manual…

I worked in a chemisrty lab, I’m used to colorimeter.

I know that we can do a lot with electronic equipment and white light!

Have a nice day


#7

Color is probably the most subjective thing in the 4C. We might be able to get a fixed view on cut, carat and to some extent on clarity (though I think on that one there’s already potential for discussions as well) but color - well, that one is enormously treacherous territory. It starts with biology, were some people perceive colors differently or are able to see more or less color than others (just look at the “blue/gold dress story”). It continues with lighting, angles etc. As so often, the devil is in the details - most might see a stone as predominantly red, blue, green or yellow but it’s those fine nuances and shifts in saturation and tone were most disagreements occur - which is further compounded by the spread of specific color terms as “pigeon’s blood”, “cornflower blue” or stuff like it. Heck, sometimes I think my mood leads me to perceive colors differently (which makes for a really bad scientific approach).

Probably Color will always be subjective. The only way would circumvent this is to precisely define the conditions and equipment under which the color estimate was taken. But I’m not so sure this really helps in the market.

I personally use the world of color set by the guide under a daylight bulb - yet even then it’s sometimes difficult to get an exact match (though I do this stuff mostly for my own personal use, so I’m not as immersed in it as a professional - which might explain the difficulties :wink: )


#8

I really thank you for your answer
I will buy the kit world of color and a good table lamp


#9

World of Color was developed to be used with fluorescent tubes of 6200K or higher (up to 6500K) daylight temperature with the highest possible CRI (color rendering index). Since the best bulbs I could find had a CRI or 82 and the OTT light bulb has a CRI of 92, I opted for that even though it’s color temperature is about 5500K. YMMV. Just be aware that your choice of viewing light does influence the color seen.

My experience so far (few months) with the World of Color system is that you can get pretty close to the “real” color by comparing the gem to the swatches and that the comparison colors that are close are within a fairly close range of prices. There is always going to be some subjectivity and bargaining room and in the end the value of a gem is what someone will pay for it, the old “between a willing buyer and a willing seller” idea.

Also bear in mind that color assessment has to take into account color performance in different types of light, too. Some stones look good in daylight but tend to muddy or close up under incandescent or other types of warm lighting and this would tend to devalue a stone slightly when compared to a stone which remains bright under warmer lighting. Then some stones will display a color shift or color change and this is generally a plus, but in the case of sapphire, if the change is from blue to another color in some light, the value is actually reduced.
HTH, royjohn