I am very fortunate to be able to attend several auctions that specialize in Heisey every year and have been for many years.   I collect Heisey and also sell a good bit of it through my eBay store and on eBay auctions.

Heisey was one of the first glass houses to mark their glass back in the early 1900's.  However, MOST Heisey is NOT marked.   Some patterns are and some patterns are not.  Even within patterns, some pieces are marked and some are not.   In the hundreds of pieces of Heisey Glass that I've handled through the years, I would say at least 60% of Heisey is NOT marked!

NO blown ware is marked.   None of the earliest patterns are marked.  Fandango and sunburst are not marked.   Most of the stemware is NOT marked!  

Many people think that IF there is a mark, then they know it is Heisey and NOT Imperial.  NOT TRUE!!!  Imperial used the Heisey mark many times.  They used it when they were making glass for Heisey when Heisey was so busy that they couldn't keep up with production.   Then when Heisey was closed in 1957 Imperial continued making quite a bit of the in-line pieces with the Heisey mark.

So how do you know if it is Heisey if the mark isn't an indication?   Buy from a reputable experienced dealer.   Learn how to look at a piece to tell the quality of the glass.   Imperial is usually a bit wavy in appearance.  Imperial colors on re-issues are not the same colors as the original Heisey colors.  Heisey glass is by far the best glass ever made for the pressed glass trade and the quality and clarity of the glass is unequalled except for maybe early Duncan and Cambridge.   If you ever have a chance to pick up a large animal figurine, it will tell you what Heisey is all about as the glass is so perfect it appears to be hollow when in fact it is solid glass!

Buy books!  There are some very good books on the market, but start with the Bredehoft book first.  It is the best all around book on Heisey.  

So when you wonder..... is it really Heisey??? Just because it isn't marked, throw that thought away!   The mark does not make the glass!