Thanks with the rim suggestion! Then it would pop more, I did not thought about that.

Maybe double post next time to have it still in my gallery.

Thanks for the feedback! Also thank you for the explanation with the value, I got a little bit blind (or nevertheless did not see it because of *beginner-eyes* :D).

Yes, the bottom one is filled to the neck :) Maybe, I give it a try in isometric perspective or jump right to next exercise.

The colours look great. I agree with Trigonomicon the ones on the top left (second column) look best to me. For instance, the first column has a darker blue on the glass which I think competes with the potion liquid in terms of value. I think the bottom row (full potion?) would look better if the liquid was in isometric perspective like the top one - so maybe it's filled to the neck of the bottle instead. But overall very good job.

Thank you for your feedback! Partly the difference is a subtle change in shading (less saturation, etc.) or a reduction of diameter of the surface.

It's a bit difficult to tell what's different about some of them, but I like the versions around the top left best. The bright red ring around the surface works, but could probably be more subtle.