Antique Ethnic Shell Necklace - Rarotanga

This is a rare vintage/antique necklace/breast plate measuring about 10 wide by 6"high. It features a large abalone shell with a woven straw design with fringe all along the bottom edge. It is held around the neck by leather cording. This piece came from a large collection of Mexican and Native American jewelry. Wrapped with the piece was a note with the name Rarotanga. From what I can find out, this is a small island in the South Pacific near Tahiti.

The previous owners of the estate were world travelers but seemed to concentrate on Mexican Sterling. How they came to own this piece, I do not know, but it is unusual.