Best bet is take it to a Jewellery shop and ask them to test it

If you want to do it yourself & dont mind rubbing it a little:
"Rub the piece of jewelry across a piece of unglazed porcelain tile. It should not make a black streak. If it does then it is pyrite.If the streak is golden yellow then it is gold. Unglazed porcelain tile can be found at a hardware store"
Cheers
Dan