Baccarat has manufactured luxury crystal since 1822. Its marks include etchings, molded marks, and labels, so look carefully before you buy – or sell – your glass.
Fostoria, in business 1887 to 1986, was among the premier crystal and glass companies and well known for depression glass and crystal. You can see many of their marks at the Glass Lovers Glass Database.
Gorham was founded in Rhode Island in 1831, and although it established itself as a silverware company, it also produces china and stemware and is sought after by collectors. Pieces may be marked with labels or stamps.
Heisey wasn’t in business very long (1890s to 1950s) but the company was an important manufacturer of crystal; they used a diamond H mark, but it can be difficult to locate on stemware.
Lenox was founded in 1889 and has a tradition of producing colorful crystal stemware for the table. They used printed marks and labels.
Waterford has been in the business of making crystal and stemware since 1783. Look for their famous etched mark and labels.