I Know Diamonds (and colored stones)
I'm currently a Gemologist at GIA in California. It's a great job, there are a lot of interesting things to know about diamonds, grading, measurements, formation, sales, the market, security (well, only so much I can say there)... etc.
I always like sharing knowledge, so if you want info for a character who knows diamonds or colored stones, works with high end jewelry, or anything of the sort, I'm your guy.
Okay, that's all for now.