18 Karat yellow gold and ametrine ring. The 19.0 carat step cut ametrine exhibits a beautiful color change from bright purple (amethyst) to a rich yellow (citrine). The center stone is flanked by groups of three diamonds set in small flowers, having a total carat weight of 0.23 carats. The ring is highly polished, and is finished with a band that has a knife edge side, and a half round bottom. The ring is a size 7.