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

For an iceberg, only a tenth is above see level, so I think that the density of ice is 0.9
However a volume of ice takes 0.9 of its when it melts, so an ice cube alone won't change the level of the water in the glass
Nevertheless with the diamond the ice cube has a density greater than 0.9, so it would take more volume before melting and also there would be less ice to melt and so less water added.
Let's do the maths: let x be the percentage of diamond in the volume of ice cube and v its volume, the ice cube has a density of d=x*3.5+(1-x)*0.9 I think, so it takes a volume of water of d*v, while the volume after the melting is equal to v*(x+(1-x)/0.9)
So the difference is equals after simplification to:
-x*2.5
So since there is a tiny bit of diamond inside the cube, the level will go down