I said I would post some drawings, so here are some gemstones. I will also post a drawing of a garnet, my birthstone, later. If you look at them farther away, it seems like they are real.
Pearl in silver setting
Yeah, I know the lighting is bad. I drew this for my sister, and her birthstone is a opal. This one specifically is an Australian black opal.
Aquamarine
Emerald