Costume Jewellery are made in brass and finished with matte/polished gold and rhodium plated. Also all our post earrings have a sterling silver pin.
P.S. Rhodium plating, also known as rhodium dip or rhodium flashing, is used to increase the durability, shine and light reflection of a piece of jewellery. Because it is a hard metal, a rhodium plated piece of jewellery will be more scratch resistant. If you have a nickel allergy, rhodium plating is a good option for you. From Pico Jewellery.