Created around 1900, this Art Nouveau 18K gold, opal and enamel pendant necklace was made by Marcus & Co., New York, and its design is attributed to George Marcus. Ordered as a special commission, the pendant is designed as a shaped black opal within a frame of chased gold iris blossoms and intertwined green basse taille enamel leaves with gold tips, reverse with high relief conforming iris buds, blossoms, and intertwining enamel fronds, with flexible champleve green enamel tear-drop pendant, all suspended from delicate trace link chain highlighted by four chased iris blossom links. This wearable art jewel of refined design and workmanship, centering on a mysterious deep blue and green opal, is an early exploration by this American firm of the sensitive naturalism of French Art Nouveau.