Moldavite from the Czech Republic and Herkimer Diamonds 

This is an adjustable ring and will 6-10

Moldavite is a forest green, olive green or blue greenish projectile formed by a meteorite impact in southern Germany (Nördlinger Ries Crater)that occurred about 15 million years ago. It is a type of tektite and a gemstone. Material ejected from the impact crater includes moldavite, which was strewn across parts of Germany, the Czech Republic and Austria - per Wikipedia