I first painted the base form to to begin shaping and forming the glass. My approach was to first create it as a clay goblet to get the form correct, and then work later to transform it into glass.
step 2 of 3
Then I began the process of transforming the clay into glass by using a layer mask, and started working on the glint that appears to give the glass its shape on the black background.
step 3 of 3
Next I continued to clean up and build up the glint, after than I added a series of adjustments (color balance and curves).