Ice Diamond Riddle SOLUTION ft. Vsauce's Michael Stevens

but wouldn't the waterlevel stay the same if the cube still floats with the diamond in it? I mean an icecube without anything in it would let the waterlevel stay the same when it melts. So if a tiny diamond is in it so that it sinks in a little deeper but doesnt sink completely then the additional sinking already adds some waterlevel at the moment you put it in so after the melting the waterlevel which the diamond would rise did already rise in the beginning. So it stays the same.