A peculiar stone that can make certain species of Pokémon evolve. It is the blue of a pool of clear water.

Used on a party Pokémon : Evolves an []{pokemon:eevee} into []{pokemon:vaporeon}, a []{pokemon:lombre} into []{pokemon:ludicolo}, a []{pokemon:panpour} into []{pokemon:simipour}, a []{pokemon:poliwhirl} into []{pokemon:poliwrath}, a []{pokemon:shellder} into []{pokemon:cloyster}, or a []{pokemon:staryu} into []{pokemon:starmie}.