Taking a break from literal gem dice to show off the best d4s ever made. Not only are these not caltrops waiting to pierce slippered feet at night when a stray one happens to be right where you're stepping in a rapid trip to the bathroom after a night of drinking way too much tea while playing RPGs, they also roll much better.
Whoever invented these is a genius.
I think we've been calling them 'pill' d4s over here.
I even made some wooden ones before they started selling them at my flgs.