Celtic Stone

Commonly referred to as a "rattleback" this solid piece of steel can be used for fidgeting on your desk like a spinning "top", but know the secret and it can also be used in magic/illusion for psychic predictions, telekinesis, or spiritual bizarre magic!

Effect: Spin the stone clockwise on a smooth surface and it will just keep spinning until it loses momentum, or spin it counterclockwise and again it just spins counterclockwise until it stops. This can be done by you or the spectator with ease.

However after a magical gesture, a magic word, asking the spirits to show their presence, or when place near an item of your choice like a chosen card. Suddenly the chunk of metal will only spin in one direction! When you spin it clockwise it suddenly stops and reverses its spin to go counterclockwise! The spectator can spin it too with the same result! There is no trick to spinning it and there is no special move to be practiced, the unique design and simple physics do all the work and it will ALWAYS reverse its direction and go the other way!

Full examinable, it's just a piece of metal with nothing to discover or expose!

See it in action:
https://www.youtube.com/watch?v=DtTGwBJ9PGw