Things You'll Need
Instructions
Examine the stem for the Heisey trademark logo. The logo consists of a raised uppercase "H," surrounded by a raised diamond that is clearly taller than it is wide. Heisey made an effort to hide the trademark logo as much as possible. That, in addition to the fact that not all stems have the logo, or the logo could have been polished off, can make this search difficult or inconclusive.
Compare the stem's mark to the actual Heisey logo. If you find a mark, examine it carefully before drawing any conclusions. There are numerous Heisey imposter pieces that have been made specifically to resemble a Heisey piece. On further examination, the mark could actually appear as a square on its side with an "H" or something similar, instead of a long, diamond shape.
Search for the piece in a Heisey encyclopedia or other text. Neila and Tom Bredehoft have published two works on identifying Heisey glass. The texts include pictures, color information and information on figuring out the value of a piece.
Contact the Heisey Glass Museum. The Heisey Collectors of America founded the Heisey Glass Museum in 1974, which contains more than 4,500 Heisey pieces. You can pay the $5 fee, as of November 2010, to have the museum identify your piece. It also requires that you mail detailed pictures and measurements of the piece. The process can take up to a month in some cases.