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

Thinking back to grade-school science using water in some container, and recording how much the level of the water rise, we can determine the volume of the object in the water. The problem is that this technique does not work well with objects that are significantly close to or and less dense than the water. Going back to the riddle, the diamond is placed in a cube of ice, which floats on the water when it is placed in it. When the ice melts the diamond drops to the bottom. Does the water line move up? Stay the same? or drop?. Given than the melted water adds more water to the original water volume, it can only move up. Also being that the diamond is significantly more dense than water, and a diamond takes up volume, it will displace some of the water moving the water level up.
Final answer is that the water level moves up, from both the added volume of the melted ice which is now water, and the volume displacing some volume adding to the rising of the water level.