The patterns of old pieces are true to patent drawings, catalog drawings, ads, etc. However, bona-fide variations are known: experimental pieces, one-of-a-kind pieces, etc. Some new pieces have been noted to have pattern errors.
f. A few European companies (principally Val St. Lambert) either copied or were licensed to produce American patterns, e.g., Bergen’s “Crescent”, Averbeck’s “Florida”, Libbey’s “Harvard”, and Fry’s “Elsie”. American companies did not hide the fact that they were selling imported glass, e.g., European engraved glass was sold in Dorflinger’s New York store; P&B sold imported cut glass as witnessed by the offerings in their catalogs.