a mother-of-pearl pearl
a flat head nail
a 20mm pendant
a 4mm ring
from the extension chain
of the chain  very fine
3mm and 4mm rings
A  buoy clasp

Ultra simple assembly,  start by  mount the mother-of-pearl pearl on the nail and form the loop.

Tip: Don't make the loop too small because the chain will have to slide through it.

Then mount the pendant on a 4mm ring.

Cut a piece of very thin chain about 45cm / 50cm. Adjust the size to your liking. Expand the links with a reamer to facilitate the installation of the rings.

Thread the pendant and pearl onto the chain.

Then at the ends of the chain, place on one side the clasp with a 3mm ring and on the other side a 3cm piece of extension chain with a 3mm ring.

Beautiful creation!