Antique Mother of Pearl (Mediterranean?)and Black Coral (Red Sea?) necklace.
Beads aprox. diameter 15 mm.
Not easy to find these larger MOP beads, as cutting is bound by the shell thickness...but the flatter areas of the shell's surface are also the really shiny ones.
The lighter coral balances the weight of the comparatively heavy shell beads.
Ps.- Alas, nothing new under the Sun...