Antique mirror is a unique mirror, with several different designs and antique mirror is made of clear float glass and tinted float glass. There are certain features to look for that will determine the value of an antique mirror. First, having the original glass is a big plus. Indeed, there are mirrors this old that still have their original glass. The next feature is the condition of the frame. Examine it closely. You will be able to see if it has been patched. And the original gilt should be still there, but it does not have to be perfect. There should be some nicks and scratches.