Sterling Silver Marcasite Green Jade Fortune Donut Curb Chain Pendant Necklace, 18" Sterling silver large oval Jade and marcasite pendant. Sterling silver 18" Curb Chain. Spring ring clasp. Jade is commonly treated and impregnated with polymers to enhance its color and improve its stability. Marcasite can appear iridescent in the light. The natural properties and composition of mined gemstones define the unique beauty of each piece. The image may show slight differences to the actual stone in color and texture.