Location: Philadelphia, Penn. and Riverside, New Jersey

Years of Operation: 1880-1956

Predecessor: C.N. Thorpe

The Keystone Watch Case factory began operations in 1880 under the ownership of Hagstoz & Thorpe. The company was officially incorporated in 1886 to consolidate several entities.

The Keystone Watch Case factory began operations in 1880 under the ownership of Hagstoz & Thorpe. The company had previously manufactured gold-filled cases under the "J. Boss" name and patent. The new factory was initially built to manufacture gold and silver cases, intended to be segmented from the gold-filled case production. These cases were marked with a Keystone symbol when the factory opened in 1880. Eventually, the Keystone Watch Case Copmany absorbed the gold-filled business operating under Hagstoz & Thrope, creating the Keystone Watch Case Company, and all cases were marked with the Keystone trademark.