These were all part of my grandma’s old jewelry collection and the sale includes 2 sterling niello earrings, a glass pendant, a small Majorica necklace which i believe is silver, a .925 silver Italian-made necklace, and a thin, possibly gold-plated cuban link necklace.
Both the Majorica and the Italian necklaces are 18” long while the cuban-link is 30”.
An offering of a hard to find Art Deco necklace.  Closure is unusual silver "C" shaped clasp which closes when you push each "C" opening together and twist. See photos of clasp and necklace.   Last photo depicts the side and back views of each asymmetrical onyx which has insets of red jasper and mother of pearl.
Approximate necklace measurement 34 1/4" from end to end.  Could be wrapped around neck twice to make a double stranded necklace.
Color in photos may not be accurate
If for any reason you are not satisfied, please contact me.