Instructions
Examine your parfait glass carefully, searching for any markings that might reveal a maker. Glass marks are typically on the bottom of a piece, near the center. They may, however, be on the outer rim of the bottom of the glass. You may need to use a magnifying glass to make out any marks. These marks may be a molded part of the glass, or may be hand etched.
Look carefully at your parfait glass to determine its style. You can use this to gauge its approximate age and its origin. Scandinavian glass looks dramatically different in style from Italian glass, for example. Depression glass and Victorian glass also tend to be very different. Once you have narrowed down its style and approximate age, you can look through the relevant antique glass books to try to find your exact parfait glass or another piece in the same pattern.
Take your parfait glass to an expert if you cannot figure out its pattern yourself. This expert may be the owner of an antique store specializing in glass, for example, or an appraiser at an auction house. Even if the appraiser does not recognize the exact pattern of your parfait glass, he can give you a general sense of when and where it was made as well as its approximate value.