It fastens at the center back with a round spring clasp

and an additional short silver chain with a shell pendant allows the fit to be adjusted

The three necklaces are:

clear-colored zirconia stone hanging underneath

literally made from 14 karat 585 solid gold

Triple Layer Geometric Chain Necklace Waterproof layering-sets It fastens at the centerTurn heads with this eye catching trio of layered chains: a mix of box, cable, and rectangular link styles that add instant dimension to any neckline. Designed in stainless steel and available in gold, rose gold, or silver, this necklace makes a statement while keeping it effortlessly cool.