International Gemological Institute's certificates

Jewelry Discussion
1

list:

does anyone have experience/opinions/knowledge regarding
International Gemological Institute’s colored stone identification
certificates?

IGI has a number of labs world-wide, making it much more accessible
than GIA or AGTA.

thanks
bill

2

Bill-

My experience is that IGI certs have very soft grading standards.
I’ve had stones certed by both GIA and IGI and they’ve always come
back with a better color and clarity grade from IGI.

So when buying an IGI certed stone I’ll discount the cert.

Be careful when selling them too. Nothing like having to apologize
to a client when they’ve had the gem reappraised.

Kim.

3 
   does anyone have experience/opinions/knowledge regarding
International Gemological Institute's colored stone identification
certificates? IGI has a number of labs world-wide, making it much
more accessible than GIA or AGTA.

Bill,

Hi again :wink:

The IGI are certainly spread around the world and are well known for
their diamond grading services together with the GIA and HRD. I do
not know a great deal about their coloured stone services, but know
that they are one of about three different labs based in Dubai. The
reports look okay from the few I have seen, but once again I bow to
those on the list who may have had actual experince sending items to
them for identification.

If you would like I can be contacted off list for any ‘detailed’
discussion on the various laboratories around the world as it is a
subject I know a little about and you appear to be interested in
learning about them. Where are you based?

Regards - Nick

4

I am not familiar specifically with IGI’s colored stone certificates.
But, here are some guidelines to follow when you look at any lab
cert. Each lab has its methodology, prejudices, strengths and
weaknesses. This is simply because the trade has managed to keep the
principles of quality grading gemstones a secret even from
themselves. Lab gemologists come from different traditions with
differing approaches and opinions. Dealers are well aware of this and
tend to exploit it, that is, they will send a stone to a lab that is
likely to give the best cert to a particular stone. So if you are
dealing with, say a padparadscha sapphire, labs have different
definitions and the dealer will send the stone to the lab whose
definition his stone fits.

Votaire said: If you would speak with me, define your terms. Until
recently labs did not even use a standard terminology and in the
trade dealers use various terms some of which are simply inaccurate.
There is beginning to be a generally accepted terminology for
describing color. GIA’s new colored stone course does follow that
terminology and by doing so has moved the standardization process
forward.

There is still no generally accepted explicite colored stone grading
system although I contend there is certainly an implicte one that
exists in the marketplace. I have tried to make the princples of this
system explicite in my book.

Richard
http://www.rwwise.com
For Information and sample chapters from my new book: