Can we wear jewelry (like rings, lockets, etc.) embossed with the forms of Perumal and Thayar? Can we wear jewelry embossed with the forms of Narasimha, Chakrathazhwar, and Hanuman?

Jewelry embossed with the forms of Perumal can be worn if made of silver or gold. It is said that ornaments made of iron and such should not be worn.
Some people wear lockets with Narasimha, Chakrathazhwar, and Hanuman. Therefore, they can be worn with good faith and devotion.