It would be the same as PKMN Pearl & PKMN Platinum. In Diamond, you can get it in The Underground & Route 213. In Platinum, you can find it in the Solaceon Ruins. You must have a Poliwhirl, a Shellder, a Staryu, an Eevee, or a Lombre seeing you want a Water Stone.
In Diamond, you can obtain a Water Stone in the underground in Sunyshore City.
Go dig underground and with luck a Water Stone appears
A diamond sinks in water. There is only one stone that floats, pumice.
go underground and keep digging till u find a water stone or a fire stone
Thunder stone =Jolteon Water stone = Vaporeon.Fire stone = Flareon.
to evolve certain Pokemon
what do you mean
evee
Diamonds do not float.
A Water Stone evolves a Poliwhirl, Shellder, Staryu, Eevee, and Lombre.
Did underground and maybe you'll get lucky!
you can find one while mining