Depends on the game in HG and SS beat the johnto elite four and go to the pokelethon
Dusk= Galactic Warehouse Shiny=Iron Island B3F Dawn=MT.Coronet(2nd)1FL.
The first one is in the Galactic Warehouse in Veilstone City. You can also dig Underground for more Dusk Stones, as well as other elemental evolution stones!
You can find Dusk Stones in Route 10 and within Dust Clouds in Wellspring Cave, Mistralton Cave, Giant Chasm, Chargestone Cave, Challenger's Cave, Twist Mountain, Victory Road and you can find some Dusk Stones lying out within Mistralton Cave.
You can find as many as you can. When you are in a cave (like the Giant Chasm) a swirling dust cloud can contain a Dusk Stone.
Dusk Stones cannot be found in any GBA game. Stones like this are exclusive to Diamond, Pearl, and Platinum. Likewise you can't find a dawn stone or shiny stone in any GBA game.
you can find dusk stone's in swirling dust in cave's. (random stones/gems and the mole pokemon) and a veteran, south to a hiker, on route 10 will give you a dusk stone.
Dusk stones/shiny stones/ dawn stones/and oval stones are items that make certain Pokemon evolve. You can get A dusk stone in the galatic building in veilstone city. you evolve happiny by giveing it a oval stone and lvling it up murkrow evolves with dusk stone you evolve Roselia by using a shiny stone you can evolve togetic with a shiny stone
There is a Dusk Stone in Team Galactic's HQ, and in an area of Victory Road only accessible after defeating the Elite Four. They can also be found with the Pickup ability.
5 but i don't know where
Veilstone City
evolve certain Pokemon
Dust Clouds in Caves.