Michigan Shaped Petoskey Stone Pendant. The Petoskey stone (Hexagonaria Percarinata) is the state stone of Michigan, and found primarily in the lower peninsula of Michigan. It is 350 million year old extinct fossilized coral. Each handmade Petoskey stone pendant on this website is found by Greg, slab cut, shaped, and polished by hand in 6 steps with very fine sandpaper until they reach their maximum shine. They vary in color, cell shape, and size. No two are the same. They are a beautiful stone, and ALWAYS the attention getter in the room! Each bail is securely attached to the stone using very strong E6000 glue. Consider purchasing a 925 Sterling Silver Chain with this item.