I use and recommend my own colored stone grading system. “Common Sense Gemstone Grading” by Jeff R. Graham copyright 2007.
This is the Gem Institute of America’s colored stone grading system. I have been told by GIA gemologists that this system is still being modified and worked on by them. So be aware there may be changes.
May 2008 – GIA is still using this basic system but they have made modifications to it. I was recently contacted by a GIA Senior Instructor and told this. When I asked for a link to or a copy of the updated grading system (so I could update this article). I got the typical GIA answer (which is one of many reasons I do not care for the GIA). You have to buy the books and course work. Trust me nothing GIA sells is cheap. My answer was when pigs fly. So if you want the current GIA system being used you will have to contact GIA and probably pay for it
Note: I would also note that GIA has created a cutting grade for the actual faceting/cutting of the gemstones.
I have listed this system because it is being used by