Following @frankbeverett, VP and sales director of Sotheby’s Jewelry in New York, is like taking a crash course in estate jewels. Glimpse museum-worthy pieces by JAR, Claflin, Belperron, and more—all via Everett’s unfussy, up-close-and-personal pics.    Boivin’s radish brooch   Cartier citrine c. 1940   Carvin French ruby ring   Paul Flato ’40s-glam pin   Raymond Yard c. 1952   Bangles by Schlumberger