Fostoria, also known as American Fostoria, is a type of glass coveted by collectors and was manufactured by the Fostoria Glass company. This company started making glass in Fostoria, Ohio, in 1887. The pieces are sometimes difficult to check with the naked eye, but there are several steps that can help you determine if you have an authentic Fostoria piece.
Slide the tip of your finger down the glass to feel for smoothness. Fostoria glass will be smooth to the touch. Other glassware can have a bumpy, rough or wavy texture due to the lack of fire polishing.
Turn on a black light in a dark room and shine it directly on the glassware. If it is true Fostoria, the glass will appear a very light yellow. Other glassware will not. This method is used by authentication experts.
Check the handles. Handles on a Fostoria piece will be attached at the top edge of the piece, while others are often an inch or so down the side.
Turn it over and look at the feet. Fostoria feet have vertical feet with S-shaped front and back.
If there is a ring around the bottom, check that it has been ground down.
Check the seams and shape. Fostoria pieces usually have three seams and more curvature or "flair" at the top of the piece. Other glassware often features straighter, simpler construction.