Granite Cave Method

• The easiest Everstone to find is in Granite Cave, which is north of Dewford Town. To reach this area, you will need to ask Mr. Briney to sail you there from Route 106. Once you're inside the cave, travel west from the entrance until you reach a ladder to the first basement level. From there, you will need to use the Mach Bike to climb a slippery slope and traverse crumbling ground until reach another ladder that leads to the Everstone.
  
  

Geodude Method

• Wild Geodude sometimes possesses Everstones. Travel to Victory Road, Granite Cave, Route 111, Route 114 or the Safari Zone to find the Pokemon. Capture Geodude in PokeBalls until you find one that is holding an Everstone. Alternatively, you can use Thief, a Dark-type attack, during the battle to steal a stone from the creature.
  
  

Graveler Method

• Wild Graveler, Geodude's evolved form, as occasionally possesses Everstones. As with Geodude, you can either capture Graveler or steal its item with Thief. Graveler is stronger than its predecessor, so expect it to put up more of a fight. These Pokemon appear in Victory Road and Team Magma's cave hideout.
  
  

Trade Method

• If you know a friend with "Pokemon Ruby," "Pokemon Sapphire" or "Pokemon Emerald," you can borrow a spare Everstone. Ask him to equip a Pokemon with the item and then use the Trade Service, which appears at any Pokemon Center in the game, to send the Pokemon and its item to your version of the game. In exchange, offer him an item he lacks. When the trade is complete, disconnect from the Trade Service and save your game file.