necklace, gold with emeralds and pearls, Gallo-Roman, mid-3rd c. (Louvre BJ586), a photo by Atelier Sol on Flickr.
That being said, there is a multi-stranded necklace in Theodora with Attendants (which is one of two of my go-to resources for art contemporary to my persona) that may resemble something like this, but like most two-dimensional pieces of art, it is hard to tell.
One more thing - check out the clasp! I've seen similar leaf-shaped clasps that have been made commercially. It would also not be hard to create one with commercially-produced products, either.
Provenance: Rouen (possibly)
l : 39.5 cm
photo source: RMN