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This would be a good use of a transmissive background like a Lastolite Hi-Lite, if you had one.
Lacking that, two Einsteins angled from the sides to light the background -- just out of frame at vase level -- and the third as key light from the front -- at whatever angle and elevation gives a good look for the subject -- would work just fine. A couple of white panels in front to reflect some of the backlight as fill will also help.
If you have a reflective black base to set the vase on, that can work well. It'll look white to the camera when backlit, but will help give a dark outline to the translucent vase to help it stand out from the background. Black cards out of frame at the sides can also help with that.
Do you have a copy of Light -- Science and Magic? It goes into this kind of stuff in great detail, if I recall correctly. (I'm at work, and my copy is at home.)