There is no single color or paint that could be labelled 'transparent glass'. The color of a glass is determined by what's around it, what you see through it, what is reflecting in it, and how much shadow there is.
The two glasses in this photo are both simple, transparent glass. The one at the front is empty and the one at the back has liquid in it. Now your brain knows that the color of the glass at the back hasn't changed, it's the liquid in it that's making it a different color. But to turn it into a painting, you don't first paint the glass itself and then what's in it.
You're creating an illusion. You need to suspend your brain's interpretation of the objects and look at the colors and tones. Paint each little shape or bit of color and tone individually and, like a jigsaw puzzle, the pieces will snap together to form the whole.