Can You Solve this Ice Diamond Riddle? ft. Vsauce’s Michael Stevens

Now the water level does not only depend on the weight of the ice or diamond it depends on the volume. Ice floats because it is less dense and water can provide the necessary buoyant force.  When the ice melts we have a diamond more dense and more importantly a lower volume. So it should not displace enough water and sink in turn *decreasing the lever of water from when the ice cube was put in*.