near pastoria
shards can be used to trade with other people. in return, they may teach your Pokemon moves. there are 3 move tutors in Pokemon platinum that will teach your Pokemon moves in exchange for shards in a specific color.
You can trade them to the move tutors so that your Pokemon can learn different moves.
you can trade them for moves i prefer to go to snowpoint city to trade them but there are other locations now speak to the hiker at snowpoint city (he lives at the house right from the temple) and ask him for the move you want from the list and trade the shards for the move
Trade star pieces for shars at Fuego Ironworks. Find star pieces underground.
There are four shards in Pokemon Platinum- red, blue, green and yellow. They can all be found in the Underground.
you get them from underground, random spots, or you can trade star pieces for a set of 1 shard of each color.
You can get them underground.
you can find them underground
The color shards you can find in Pokemon Platinum are Red, Blue, Green, and Yellow Shards.
There is a small house very close to Pastoria City and to it's left. In that house, you can trade the shards (10 for each TM) for weather changing moves. 10 red shards will get you sunny day, 10 blue will get you rain dance, etc.
you cant, you can only exchange heart scales to relearn moves or you can exchange 10 shards the same color for a TM
you can trade shards for stones in hunters house. His house is southwest of mossdeep.