9mm across, not including bail (about 5/16 inch). Hole is about 1mm wide.
Both sides are basically identical. The gold rim is slightly more pronounced on one side than the other, but there's no "bad" side. Crystal is faceted for sparkle.
These are glass crystals, not precious stones.
I get a lot of questions from people wanting to know how many pieces are being sold in a listing. I'm very sorry but I cannot answer most of these, due to time constraints. The quantity is always clearly stated in the title and first line of the description.
At the top of the page, next to the price, you will see how many *sets* of this quantity are available.