This is the most common form of scrying device, a crystal sphere about 6 inches in diameter.

A character can use the device to see over virtually any distance or into other planes of existence, as with the spell scrying (Will DC 16 negates).
Certain crystal balls have additional powers that can be used through the crystal ball on the target viewed.

Prerequisites: Craft Wondrous Item, scrying.
Cost to Create: 21,000 gp, 1680 XP, 42 days.