Shading Exercise - Glass/Liquid/Ice
Hope you like it
Also, ice doesn’t sink to bottom in a glass of water. 
// Short explanation: Water starts expanding as it gets colder than 4°C (physical wonder ;). Consequently, ice is less dense & has larger volume, yet retains same amount of mass, thus it floats in same substance/matter.
Next thing, what are those stripes - on edges at the top of the glass?
Getting back to physics, May be it is not water in the glass, something with slightly less density like oil or alcohol.
Could be
I mainly assumed based on color of the “Liquid” (oils and similar were instantly excluded, based on probability of getting these liquids served in such arrangement). While scotch, whisky, bourbon & maybe even rum aren’t strong, pure enough (based on density, drink must have at least 86% of alcohol for ice to sink to bottom). Tea or coffee are mainly water. So the only argument left for me was, that those “Ice rocks” are basically made of glass. Then they would keep cold, wouldn’t melt, would sink to bottom & have different IOR. Problem could easily be solved, if title weren’t so descriptive. 
Yet still, there’s so much detail missing to stop any speculative guessing…
Glass cubes in coloured water in container made of ice. Problem solved? :]
That looks more like whisky rocks to me…
on the rocks
hard to notice, but i assume, rocks goes to bottom because tops/peaks are not submerged
ie.