Out of these studies, I think I managed to capture the reflective properties of the glass pebbles and glass bottle particularly well. You can see that the glass bottle is supposed to be transparent through the shadows and strong contrasting highlights used to represent the light being refracted through the glass. I think my ellipses need work though, as some of them are slightly off in shape and are sometimes not equal on both sides, like on the metal jug.
Here is another glass that I did in pencil. Pencil is good for glass surfaces as it is easier to do fine details such as the reflections in the glass.