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The Encyclopedia of Horology

Philadelphia, United States

Keystone Watch Case Co.

Partially verified

Cases

History

Giant producer of watch cases for many brands.

Major innovations

    Known markings

      Serial numbers

      This archive holds no verified serial-number table for this maker. Do not date a piece from its serial number alone; use case hallmarks, movement construction, trade directories and documented comparison examples.

      Collecting significance

      Originality of dial, hands, case and movement is the main consideration. Confirm that the movement belongs to the case and that the dial has not been refinished, and record what is verified separately from what is inferred.

      Diagram

      bezelcrystalback and cuvetteband, bow and pendant
      Schematic: case construction. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

      Sources & references

      1. Kathleen H. Pritchard, Swiss Timepiece Makers 1775–1975
      2. Brian Loomes, Watchmakers and Clockmakers of the World
      3. Mikrolisk trademark and maker index
      4. Published trade directories and period material catalogues

      Where sources disagree, the disagreement is stated rather than resolved silently.