![Art Deco Black Mother-of-Pearl Cuff Links. Art Deco Black Mother-of-Pearl Cuff Links.](https://www.langantiques.com/university/wp-content/uploads/elementor/thumbs/art-deco-black-mother-of-pearl-cuff-links_1_130-3-10060-q88jyzby33a68sjko823pa4djiaigc2svd70r51sp4.jpg)
A dark organic substance secreted by some invertebrate animal life including coral polyps and pearl-producing mollusks. Conchiolin is the binding agent in nacreous layers of pearl and mother-of-pearl shell. It is also the material that forms black and golden coral.