Bolsters in nickel silver
Nickel silver is an alloy of copper, nickel and zinc whose name describes its color, not any silver in the metal. The Copper Development Association says nickel silvers are also called nickel brasses and that "the silver refers to their attractive silver luster." On knives, Böker says the alloy is mainly used for fittings, especially bolsters.
The silver in nickel silver is a description of the color. The Copper Development Association says nickel silvers "are alloys that contain copper, nickel, and zinc", and none of the sample compositions it lists includes silver. The CDA also calls them nickel brasses, and Böker's knife glossary says the material is "also known as German silver."
Nickel silver is a family of alloys, not one recipe. The CDA describes cast nickel silvers as copper, tin, lead, zinc and nickel alloys that take the same name from their "silvery luster", and the composition ranges Böker and the CDA publish disagree, so this entry prints none.
Böker says that in the knife industry nickel silver "is mainly used for fittings, especially for the so-called bolsters", and Case's own product page for a Canoe names "nickel-silver end bolsters". What a bolster does has its own entry.
On this site the phrase shows up in the product data of Case, Böker and Buck traditional knives that list nickel silver bolsters, such as the Case Canoe, Böker thuya wood lockback, Buck Prince lockback and Case Sowbelly in the grid below. A Case pattern number codes the handle material but not the bolster metal, as reading a Case pattern number shows, and the maker itself is profiled on the Case brand page.