<p>Tough question. Gaining knowledge of Westmoreland's production colors and markings is the best way to learn whether your piece is a reproduction. There is a difference between a reissue and a reproduction. Westmoreland often would pull out an old mould from days gone by and start producing again. This would be a reissue. &nbsp;Plum, Rosso, Fenton, Mosser, Summitt, A.A. Importing and other glass companies purchased Westmoreland moulds and started producing from them. These would be reproductions. Most often the Westmoreland mark has been removed but not in all cases. &nbsp;For example, Plum Glass Company of Plum, Pennsylvania was founded by former Westmoreland workers and never removed the Westmoreland marks from the moulds. On the other hand, Rosso Glass always removes the Westmoreland mark. Generally you can tell if it is a reproduction by the color or decoration. You can always post a picture of piece in the various glass forum sites on the Internet and Facebook or you may contact the Webmaster at westmorelandglass@gmail.com if you have a question.</p>