Diamond merchant Isaac Pointz and his guests have come ashore at Dartmouth to enjoy the fair after the yacht races. Over dinner, young Eve Leathern bets she can make Pointz's famous diamond, the Morning Star, disappear right at the table. When the girl does exactly that, she discovers she has made the priceless gem disappear more completely than intended. Fortunately, Parker Pyne is able to get to the bottom of what really happened to the Morning Star. Librarian's note #1: an earlier version has Hercule Poirot as the lead character, with minor differences. Thus the entry on Goodreads shows both as leads. Librarian's note #2: this entry is for the story, "The Regatta Mystery." Collections and other short stories, including the collection with this as the lead story, by the author are located elsewhere on Goodreads. Individual entries for all Poirot short stories can be found by searching Goodreads for: "a Hercule Poirot Short Story," and the same for Pyne short stories: "a Parker Pyne Short Story." Librarian's note #3: the story is available in the anthology, "The Regatta Mystery and Other Stories," as well as elsewhere. It first appeared in "Strand Magazine" in 1936.