You know you’ve made it when you’re known by a single-name moniker — Madonna, Halston, Iman. And jewelry designer JAR, a.k.a. Joel Arthur Rosenthal, has certainly made it. Ever since the Bronx native decamped to Paris in the Sixties, he’s catapulted himself into that rarified world of Place Vendôme jewelers, not the easiest of cliques to crack. His clients have included Elizabeth Taylor, Princess Firyal of Jordan, Ellen Barkin and Francois Pinault. Meanwhile, his jewelry — breathtakingly crafted and seemingly painted with pavé stones — simply mesmerizes. Check it out for yourself at the impressive Jewels by JAR show at the Metropolitan Museum of Art, its first-ever exhibit dedicated to a contemporary jeweler — or as the museum dubs him, an “artist of gems.”