Blender/Luxrender:
the Amethyst (Purple) gem was modelled using "stupendoustugb's" Excellent YouTube tutorial on "Modelling a Diamond in Blender".
The Lonestar (blue), Emerald (green), and Princess cut (red) were modelled using "amagammonon's" First Class YouTube tutorials on "Realistic Gemstones".
I've done some gemstone in Blender myself, but you've done a better job than I did. Plus on top of that, you have my birthstone - the amethyst.
Great job!
Very excellent. I want to learn to make beautiful gems like yours. Thanks for the tutorial suggestion. Thank you.
nice render scene, sir.