Antique serpent snake necklace, early 20th C. costume

Rare antique early 20th C. circa 1900- 1920s serpent snake necklace with paste/ rhinestone twist head and amethyst stone drop pendant. The head screws off to remove the necklace from the center coil to take on and off. Silver and gold-tone metal chain, fluid in movement and adjustable in size. Measures: 21.5" total length/ lying flat and opened up completely.
Condition Report: Excellent, very nicely kept/ wearable.