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

If the ice cube really floats, then I'll say that the water level will rise. This question seems similar to the boat riddle but the "boat" in this case reacts in a different way. While floating, not all of the volume of the ice and diamond is displacing the water, but when it melts all of their combined volume displaces it. Though, I still feel like the ice should sink if it has a diamond in it at the start unless the diamond is really small.