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Need some help on diamonds


#1

Hi!

I need some opinions from the diamond experts here. One of our
students in our diamond class is insisting that all diamonds are
currently graded under 20X. He does not take our word that is
not so. So, I would appreciate some comments here. Especially,
from Mr. Roskin whose book is one of the best on clairy grading.

Thank you!

Eva M. Ananiewicz
Tampa, Florida


#2

This person is not correct… the industry standard for grading
is 10X

Best regards,

James Marker <@James_Marker1>
GIA Online <www.giaonline.gia.edu>


#3

If you believe the GIA, diamonds are graded at 10x. (This is
also the FTC rule on clsrity grading. However, I have seen GIA
instructors use higher power magnification, i.e. 20-30x, and then
go down to 10x for final report.


#4

Comment of on 20x loupe for grading a diamond.

Standard in the diamond trade for clarity grading is a 10x
loupe. I have seen people using 14x loupe but 20x is too much.
Anyway standard practice is 10x loupe.

Try it and you will know.

Regards,

Tay


#5
.  One of our students in our diamond class is insisting that
all diamonds are currently graded under 20X.  He does not take
our word that is not so. 

Hi Eva,

All you have to do is guide your student to GIA for a
clarification on grading.

Regards,

Barry Hansen
Hansen Designs (newly moved to Lake Elsinore, Ca. where it hasn’t been
under 100 for much of the summer).


#6

Your student is wrong. GIA sets the standard, which is now and
has been since it’s founding in the 1930’s, 10X magnification for
stone grading. If there is a clarity characteristic that you can
see at a higher mag., but you can’t see it at 10X, it doesn’t
exist for the purposes of grading. Tell your student to call GIA
or look it up in one of many fine books on the topic.

-Elaine
Chicago, IL, US
Midwest
Where everyone has gone back to school…the fall weather can’t be far behind.


#7

Hi Eva,

I’ll bet your student has a bumper sticker that says, ‘Question
Authority’ on his car too.

Here’s a quote from the 1st lesson of the GIA diamond grading
course; “The FTC considers it unfair trade practice to use the
term “perfect,” alone or in combination, for any diamond that
shows any clarity characteristics under 10X.”. Clearly stricter
grading requirements i.e… 20X, would not be advantageous to the
diamond business. This is not to say that for some scientific
application 20X or even higher magnification may be required.

Lesson 2 of the GIA Diamond Grading course makes the following
statement; “Always grade at 10X, though.”

It’s common practice to use higher power (greater than 10X) for
examining a stone when plotting the inclusions for future stone
identification.

Dave Arens GG


#8
   I need some opinions from the diamond experts here.  One of
our students in our diamond class is insisting that all
diamonds are currently graded under 20X.  He does not take our
word that is not so.  So, I would appreciate some comments
here.  Especially, from Mr. Roskin whose book is one of the
best on clairy grading. 

Eva,

There are idiots in any class that won’t believe their
instructors. Maybe he’s confused though. While the standard for
diamond grading states a 10x corrected magnifier, most graders
use a binocular microscope. So each eye is seeing 10x. Maybe he
wants to add the two together? Or perhaps he’s referring to the
practice of many gemologits with zoom scopes to at least look at
the stone under higher magnification, even though grading calls
must be made on the basis of what’s visible at 10x. Checking
with higher magnification with a zoom scope is an easy way to
make sure one has not missed something silly. But this should
be explained as “cheating”, not as the standard. The standard
doesn’t even require a binocular scope or darkfield illumination.
A lot of old timers in the industry are quite happy to do most
of their day to day grading just with their loupe. The 10x one.
You can’t see as much with a 20x loupe. Too short a depth of
field, and even with a hastings triplet, at 20x, you’re starting
to get significant distortion.

You know all that already of course. This is just something to
print out to back you up. the GIA standards, similar to other
standards around the world in this respect, specifies only 10x.
So do FTC standards for diamond grading. Whether certain graders
choose, on their own, to also use higher magnification for their
own peace of mind is their own business. Some do, many do not.
All must use the visibility of inclusions at 10x as the actual
basis for their grading decisions.

Peter Rowe G.G.


#9

Hello Eva,

For diamonds : the standard clarity grading is to examine the
stone with a 10X loupe corrected for chromatic and spherical
aberration, in adequate light. Stone over 1 carat and larger must
be graded with a 10X binocular microscope that is outfitted with
dark-field illumination.

Best regards,

Francoise.


#10

Dear E. Ananiewicz, 10X is regarded as the definitive
magnification for clarity grading in Australia, and to the best
of my knowledge that’s an internationally accepted basis. Of
course diamonds are going to be examined at higher mags - I do it
myself - but 10X is the standard for assessment. hope this helps,
Rex from Oz


#11
If you believe the GIA, diamonds are graded at 10x. (This is
also the FTC rule on clsrity grading. However, I have seen GIA
instructors use higher power magnification, i.e. 20-30x, and then
go down to 10x for final report.

I’ll admit to cheating as high as the microscope will let me go,
but only what shows at 10x goes on a grading report. It’s what
you see at 10x that matters. All the definitions of clarity as
set out by GIA use 10x. 20x may help you see more clearly, but
"obvious" at 20x clearly isn’t necessarily “obvious” at 10x, no?
As for loupe grading…higher magnifications pose their own
special problems. I’ll stick to my 10x loupe, thanks.

Kat Tanaka (GJG)
@Kat_Tanaka


#12

Having just passed my diamonds final for GIA I can assure him
that all grading is down under 10x. It is not uncommon to go to
a higher power to identify the type of inclusion, but if you
can’t see it under 10x it doesn’t count.

Sharon Z.


#13

The following note was correct. If some specific power is not
chosen, there is no way to determine a grade. “Flawless” in a gem
is defined as no flaws visible to an “experienced grader” at 10X.
This is official in the US and accepted in most other countries.
If the power is great enough, any gem will show imperfections.
Some of these can are used to determine if a gemstone is
synthetic or natural, country of origin, etc.

TOM (OWL1)
@Thomas_Roginski
http://owlnest.ptd.net/gems4.htm