Two possible ways:
The first way is Getting your HM #3 (Surf) and teach one of your pokemons this HM.
At the right exit of the first gym city (Which called "Oreburgh") there is a cave.
As soon as you enter the cave, you'll see water you can surf on. Just continue surfing till' you reach the other side, there you find the Shiny stone inside a pokeball.
The other option is simpler, and you need no HM, and its a little bit longer.
From the city "Canalave" you can take go to the Iron Island, there, inside the cave, the Shiny stone placed at the very end of it.
After the National Dex, you can get as much as you want in other ways, such as:
Get a pokemon with the ability "Pick-up" in level 51+,
after each ballte, there is a chance it holds one.
Or you can go underground and look for one, but its much harder and you need a lot of patience.
All other ways contains hacks, codes, cheats, or you need to trade with someone who has it.
Sorry if my terrible English creeped you out, and I hope I helped =D
The first way is Getting your HM #3 (Surf) and teach one of your pokemons this HM.
At the right exit of the first gym city (Which called "Oreburgh") there is a cave.
As soon as you enter the cave, you'll see water you can surf on. Just continue surfing till' you reach the other side, there you find the Shiny stone inside a pokeball.
The other option is simpler, and you need no HM, and its a little bit longer.
From the city "Canalave" you can take go to the Iron Island, there, inside the cave, the Shiny stone placed at the very end of it.
After the National Dex, you can get as much as you want in other ways, such as:
Get a pokemon with the ability "Pick-up" in level 51+,
after each ballte, there is a chance it holds one.
Or you can go underground and look for one, but its much harder and you need a lot of patience.
All other ways contains hacks, codes, cheats, or you need to trade with someone who has it.
Sorry if my terrible English creeped you out, and I hope I helped =D