Yes, you can find a King's rock, but it is very tricky to actually get one. First, you need a Pokemon like Meowth, who knows the pick-up ability. Once you have done that, you need to beat the Elite Four, and get the National Pokedex. Next, locate a wild Poliwhirl, and defeat him. When you look in your items' bag after the battle, a king's rock might be in there. If not, try again. There is another way though, but you have to have beaten the Elite Four, and obtained the national Pokedex for it too work. Go to the Pal park, and migrate a Pokemon from Fire Red, or Leaf green. Make sure they are holding a King's Rock before you migrate them to Diamond.
You can also get a Pokemon that knows Covet (like Illumise) or Thief (wich is Tm 46) and battle a poliwhirl. Use Covet and there is a 5% chance you'll steal a King's rock. You can find a Poliwhirl while Surfing at route 225 by fishing with a super rod, and 227 or 228 by surfing. Good Luck!
I tried the pond above the Resort Area where the sandstorm area is located on route 228 to do this. I recommend having a Butterfree with comound eyes because this ability attracts pokemon with held items increasing your chances..also for me it helped that I had a level 100 Linoone with Covet..the first Poliwhirl I ran into was holding a King's Rock! :)
------------
There is a King's Rock in Celestic Town as a hidden item.
You have to have a Friend kings rock poliwhirl first put your kings rock on poliwhirl then get A friend to trade and trade back
you can find a kings rock on seven island in sevault canyon.
you find it in cerculan city, right then you will find a pokeball, pick it up, it is a kings rock
You find the kings rock in the very bottom of the Slowpoke Well (Near the town with the bug Pokemon gym)
the moss rock is in Eterna forest
whare do you get a kings rock in Pokemon dimond?
donuts.
You have to have a Friend kings rock poliwhirl first put your kings rock on poliwhirl then get A friend to trade and trade back
you can find a kings rock on seven island in sevault canyon.
You cant
you find it in cerculan city, right then you will find a pokeball, pick it up, it is a kings rock
give poliwhirl the kings rock and link trade it then it evolves.
You find the kings rock in the very bottom of the Slowpoke Well (Near the town with the bug Pokemon gym)
In the Underground.
The king is sat on it
the moss rock is in Eterna forest
never heard of it