Aquamarine Pendant necklace earrings set Mexican Silver

The "stones" are an aquamarine colour and appear to be imitation on close inspection with a magnifier. The part that wraps around the stones to hold them is made of Mexican 925 sterling silver. The pendant is stamped. The metal holding the earrings is not stamped but also tests positive as sterling silver. The chain is not magnetic but does not test positive as silver, so I do not know what material it is. The chain length is 16" or 40.5 cm.