WM

The "WM STER" mark combines the maker's mark for the Wheeler Manufacturing Company with "STER", an abbreviation certifying standard .925 sterling silver purity. Founded in 1946 by Frank Wheeler and based in Lemmon, South Dakota, Wheeler Manufacturing became a major producer of Western, Southwestern-style, and souvenir jewelry distributed throughout national parks, trading posts, and regional gift shops across the American West.

Pieces bearing this mark are typically commercial productions with strong Western or desert themes, such as cast rings, cuff bracelets, and pendants featuring eagle motifs, arrowheads, feathers, and bezel-set cabochons of turquoise, agate, or chalcedony. The stamp is usually struck in clean, sans-serif block capital letters inside ring shanks or on the flat reverse of pendants, occasionally accompanied by a small copyright symbol.

This mark should be distinguished from individual Native American silversmiths with the initials "WM" (such as Wayne Muskett or Wilford Begay), whose work is generally handcrafted rather than commercial casting and often features full signatures or distinct pictographs. It should also not be confused with earlier English sterling hallmarks carrying "WM" maker marks or vintage Mexican silver purity codes.