How Do I Get More Shards In Pokemon Platinum?

Usthe explorer kit to go underground and dig.
Theyre not hard to find and you get loads of them.
Also if you go to fuergo ironworks and find the route to the guy near the boiler if you give him a star piece he will give you 1 of each colour shard. You can give him as many star piees as you get :3

You can find them underground