RAPAPORT... A number of large diamonds will feature in a May 2 jewelry sale at Heritage Auctions, including a 21.93-carat stone estimated to fetch up to $250,000.The round brilliant-cut, W- to X-color, VVS2-clarity diamond necklace also has baguette-cut diamonds set into the chain, Heritage Auctions said last week. The piece is owned by a private seller, who will also offer an unmounted round brilliant-cut, 17.39-carat, S- to T-color, VS1-clarity diamond with a high estimate of $200,000. Part of the same collection are a ring set with a round brilliant-cut, 12.49-carat, O- to P-color, VVS2-clarity diamond - estimated at up to $175,000 - and a flower-themed brooch containing a round brilliant-cut, 4.15-carat, E-color, VVS2-clarity diamond with a high price of $120,000.Other notable items include a purple sapphire and diamond necklace by Cartier, estimated at up to $120,000, and a Van Cleef & Arpels diamond, black silk and leather necklace and bracelet. That set is expected to go for $80,000 to $100,000.Heritage will also sell a group of 20 pairs of earrings by JAR. Amassed over the last 10 years, it is the largest private collection of composite, titanium and aluminum ear clips by the designer ever to be auctioned, the company said.Meanwhile, jewelry that belonged to Joan Crawford, including a necklace, brooch and bracelet set she wore in the 1941 film When Ladies Meet, will go under the hammer, as will 15 pieces belonging to actress Mitzi Gaynor.Image: The 21.93-carat diamond necklace. (Heritage Auctions)