Just the chain is marked 1/20 12k Gold filled and Magnet on the other side of the spring clasp.  It does not have magnetic properties.

The locket is not marked any where so I can't be sure what it is made of.  It's very pretty with the initials M H on it. It measures 1.5"by 1.5".  The rope chain weighs 3.38 grams and total weight with locket is 12.31 grams.

Locket opens and closes well.

Comes in a gift box.