Marco Bicego Jaipur 18K Hand Engraved Mixed Stone Necklace, 30". 18K yellow gold/citrine/amethyst/green and pink tourmaline/blue topaz. 30"L. Lobster clasp. Almost all gemstones and black diamonds have been treated to enhance their beauty and require special care. Photo may have been enlarged and/or enhanced. Gemstone Treatment and Care. Country Of Origin: Made in Italy.