Necklace identity

[Pete saulz]

 

[VRBeauty]

I’ve seen barrel clasps like that before. They were popular in vintage-style costume jewelry in the 1970’s or so. Are there any markings on your necklace?

 

[Paisley2628]

Your necklace appears to be from the art deco era. They are known as a "briolette" necklace- glass crystals dangling from a paperclip chain. I have owned several of these style necklaces.
Here is an example:
https://www.ebay.com/itm/Vtg-Art-De...=item363cf971b1:g:ZjAAAOSw01JbjXEq:rk:10:pf:0