Mounting a vessel sink requires specific hardware. This is especially true if #1 your vessel is glass, and #2 if it does not have a flat bottom. If the bottom of your vessel sink is rounded, then you will need to use a mounting ring, which is positioned between the countertop and the vessel sink. By placing your glass vessel sink on a mounting ring you protect both your sink, as well as the surface it rests on, especially when all the plumbing is tightened. Normally the mounting ring's finish will match that of the bathroom faucet and sink drain.