Displays on the lapidary arts feature faceted gemstones and cabochons made from Arizona minerals. He also used cabochons, which were convex, polished gemstones, rounded rather than faceted. Somewhat resembling fine jade, williamsite is cut into cabochons and beads. Banded or iridescent varieties are cut and polished into cabochons for jewelry making. These rubies are cut into cabochons to display the effect properly. Ammolite is usually fashioned into freeform cabochons and mounted in gold, with diamonds as accents. Microscopic acicular inclusions in some elbaite crystals show the Cat's eye effect in polished cabochons. Later, during the 14th century, medieval lapidary technology evolved to include cabochons and cameos. Translucent material is sometimes cut into cabochons. The decorations include embedded cabochons of shaped and polished coral. Both varieties of this stone are commonly sold as polished cabochons. It is sometimes used in jewellery where it is fashioned into cabochons. An exception is cabochons on some watches' crowns, which are round. The usual shape for cutting cabochons is an ellipse. Cabochons are smooth, often domed, with flat backs.