These are resin cast magatama, fashioned after the Ace Attorney artworks. I created the master cast some two years ago (I was learning how to use polyester resin!) and ended up with three of 'em, but ultimately chose the middle for my Mia cosplay which I debuted @ AX 2011.
They're custom dyed, wet sanded to perfection, and resurfaced using a special clear resin spray. The first two have a pearlescent quality which I love! Since they're resin and not cheap sculpy, they're going to last much longer. :3 For serious, these are hard like rocks. xD;
*Note* I am no longer taking commissions on these, very sorry!