Awesome job! very good work. My one critique, which honestly would not be noticed by most, is that the lighting on the gem is upside down.
With gem stones you places the darker and lighter sides the opposite of what you would think and then place a very bright spot of highlight in the darker area. Because gems are at least semi transparent the light refracts through them and the most light will be visible from the bottom The bright spot on top is where the light is actually hitting the gem.