This smoothly polished weapon is set with a ruby, a fire opal, a yellow topaz, an emerald, a blue topaz, a sapphire, and an amethyst.
Whenever you score a successful critical hit with this weapon, multicolored light springs from the gems and cascades along its blade or head, subjecting the target to a prismatic spray effect (save DC 20). This effect activates even if the target is not normally subject to extra damage from critical hits.
Prerequisites: Craft Magic Arms and Armor, prismatic spray.
Cost to Create: 15,000 gp, 1200 XP, 30 days.
Source: Magic Item Compendium, page 40. Originally published in Miniatures Handbook, page 41, where it was listed as a +3 bonus instead of a fixed property price of +30,000 gp.