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Non GIA Color Grading---AAA, etc


#1

Carol:

As far as I know it may have originated with eggs (grin)!
Seriously, I have never run across a standard for this in my GIA
course or anywhere else. I think these grades would mean
whatever you (or whoever) decided to make them mean. They are
ordinal rather than ratio scaling, meaning that AAA is better
than AA is better than A and that’s about all you can say for
sure. In other words, AAA could be $1/ct or $200/ct and then AA
could be from $199/ct down to $150/ct or down to $30/ct. The
absolute value of the grade is not specified, nor is the "width"
of the category either. We had a discussion about color grading a
while back on Facetor’s Digest and no one came up with a really
good standard except for the GIA Gemset or the GemDialog system
and both of those are fairly costly. HTH.

Roy(Jess)


#2
As far as I know it may have originated with eggs (grin)!

That’s about the best definition yet! :> Thanks to all who replied!

    Seriously, I have never run across a standard for this in
my GIA course or anywhere else.  I think these grades would
mean whatever you (or whoever) decided to make them mean.  They
are ordinal rather than ratio scaling, meaning that AAA is
better than AA is better than A and that's about all you can
say for sure.  In other words, AAA could be $1/ct or $200/ct
and then AA could be from $199/ct down to $150/ct or down to
$30/ct.  The absolute value of the grade is not specified, nor
is the "width" of the category either. 

That’s certainly the consensus of everyone I heard from.

We had a discussion about color grading a while back on
Facetor's Digest and no one came up with a really good standard
except for the GIA Gemset or the GemDialog system and both of
those are fairly costly.  HTH.

I’m using the GIA GemSet myself, and while there are some colors that
seem to fall in the cracks, it does seem to be one of the main games in
town and very usable. Now if we could only make rough disclose its true
colors …

Thanks again,
Carol


| Carol J. Bova @Carol_J_Bova |
|http://www.bovagems.com/ Faceted African Gemstones |
| P.O.Box 5388 Glendale, CA 91221-5388 USA |
| The Eclectic Lapidary e-zine |
| http://www.bovagems.com/eclectic/ |
’’


#3

Hello Jess: Please tell me more about “Facetor’s Digest”.Is it a
gemology forum? I am presently taking GIA home study for my GG.
How are you likeing it?

Michael Mathews Victoria,Texas USA