I have painted a Dragon's Eye using metallic brown and gold tones, and put it into a silver coloured keyring.  Each Dragon's Eye has been handpainted onto the back of a glass cabochon using a variety of paints and laquers.
 
The key ring is a split pin type.
 
The eye is 1 inch / 2.5 cms in diameter, and the total length of the keyring is 2.75 inches / 5.5 cms