Is it a pebble? Is it a flower? No it's a human molar. Be warned, people will look at you weirdly.
I had two large molars pulled out a few years ago and suddenly the idea came to me that I should make some jewellery out of them!
Everyone now thinks I am incredibly weird but honestly it is my favourite ring.
You could use any tooth, from any animal, just choose one so the base roughly fits on the circle of the plain ring.
Get the bottom of the tooth and rub it along the sand paper so that the bottom of the tooth is flat
To make sure the tooth doesn't move when it's drying, I usually get a lump of blue-tack or plasticine and sit the ring in it vertically.
Now to creep out people and make boys rethink their plans to ask you out.