Hi Deborah -- since you're not oxidizing your PMC, you'll have to rely on just the texture of the silver and the finish on the silver to communicate it's appearance.
It looks like maybe you only lightly brush-finished your surface, so you are still dealing with a porous surface which is not particularly shiny and won't photograph very easily (a shinier surface will photograph a little more lively); but it does look like you have a surface pattern on the PMC, which you could emphasize with the right lighting (or you could always oxidize it with Liver of Sulphur and buff the raised portions of the surface pattern to emphasize the pattern).
What you might try is "directed diffused" light. It looks like you photographed it with two lights at 45 degree angles, which is the "standard" set up for object photography, and is generally the right thing to do (it fills most shadows and shows surface colors well), but "directed diffused" light is used to cast light across texture in order to have the mild shadows show detail and texture.
To create "directed diffused" light, one way to approach it might be to use your exact same set up, but turn off one of the lights. If that does not provide you with enough light to take a good exposure, then try just moving one of the two lights further away, or hang a sheer piece of cloth in between one of the lights and the PMC and glass vessel. (Or you could even introduce a third light to cast the shadows.) The whole idea being that you want the lighting that you see to emphasize the texture on the piece. You'll know it when you see it.
Holly is right, the combination of silver and glass can be a tricky one to photograph -- and glass is tricky all by itself
!