There are only 2 evolutions:
Togetic---->Togekiss
Roselia---->Roserade
^^
Using a shiny stone
Roselia
You can find a Shiny Stone in Route 228 in Pokemon Diamond and Pearl. In Pokemon Platinum, you can also find a Shiny Stone on Iron Island.
In the underground.
they evovle certain pokemon. Oval stone is used to evolve Happiny into Chansey. shiny stone evovles Togetic into Togekiss and Roselia into Roserade.
it evolves by holding oval stone and level up in daytime
End of Iron Island
Iron Island B3F.
if you dig underground you'll eventually find thunder stone then after a while you'll find shiny stone ;^)
the Pokemon that shiny stone evolves is Togetic -> Togekiss Roselia -> Roserade
togetic into togekiss and rosiela into roserade
in Pokemon diamond and pearl, its in iron island