Stardust is an item introduced in the Generation II games. This item doesn't do anything, but can be sold for 1000 and bought for 10000. In Generations II and IV, it can be sold for 900. This item is found in various locations in all of the Pokémon series. In all of the games, it can be held by a wild Staryu for a 50% chance while in Pokémon Black and White, Starmies also can hold this item with a 50% chance.
II: Pretty, red sand. Sell high.
III: A pretty red sand with a loose, silky feel. It can be sold at a high price.
IV: Lovely, red-colored sand with a loose, silky feel. It can be sold at a high price to shops.
V: Beautiful red sand. Can be sold at a high price.