Vintage hematite beaded necklace with signed silver pendant

This necklace is composed of round hematite beads with a hematite oval pendant set in sterling silver. Hematite is a shiny gunmetal gray. It's not marked 925 but it tested positive for sterling. Measures 18" long with a screw clasp, the pendant is 1.25" long. The back of the pendant is marked SL Shepherd who apparently is the artist who made it. I couldn't find any information on it, it looks vintage. Please note: The pendant is not removable.