With the recent update, a new item was introduced in Pokemon Go: Star Piece. In previous Pokemon games this was only to get ingame money and minor other things (source). Because there is no currency as such in Pokemon Go, what can I do with it?
Pokemon-go – What use is a Star Piece
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Best Answer
This new item increases all of your acquired stardust by 50% for 30 minutes per use. So basically what a lucky egg for experience is, a Star Piece is for stardust (but with 50% extra, instead of doubling it).