Mexican Sterling Silver Necklace. Â For sale is a very nice heavy Mexican sterling silver necklace. The necklace is made with alternating silver cubes and silver balls. The length of the necklace is 24 Â¼â and each little square is a little over Â¼”. It is marked: Mexico; #925 and weighs 4.40 oz, with a slide lock clasp. The necklace is in very good condition.