Shiny Stones are introduced in Pokemon Black and White. They are used to evolve certain Pokemon, but they weren't available in the older generations like SoulSilver.
Here are some Pokemon that evolve with a Shiny Stone in later generations:
* Roselia (to Roserade)
* Togetic (to Togekiss)
If you're playing Pokemon SoulSilver, you'll need to find other ways to evolve these Pokemon.