Diabolo trick: Leg Orbit (Around the Leg)
For a full description and more tricks for diabolos check http://www.diabolotricks.co.uk/trick/leg-orbit.html
Hold the plate by it's edge and spin it so that the rim stays in contact with your thumb. After a single spin catch it again. Once you've mastered singles try longer spins. This trick is very versatile and can be used to add lots of flourishes.