VTG , 'Victorian Style LONG BLACK BEAD ' Mourning' NECKLACE

Vintage , Victorian style ' mourning' necklace Long black graduated-size bead necklace w faceted beads Approx 30" long tip to tip, so it has a 15" drop length Features a hidden 'screw' closure tip made of wood - which helps identify its vintage and these beads are on a thin black cotton (or silk?) cord, and the closure end is knotted. Due to its age I have not tried to un-knot it, in case the cord is delicate. So, not sure if the hidden screw closure is functional. It is long enough to just slip over your head - Beads seem to be plastic-type material, but unsure, could be jet ? Thank you - Hope you like it