E9. The Adventure Of The Western Star

Poirot warns the famous Marie Marvelle, to give up her hold on the precious jewel, when she shows him the letters demanding the return of her magnificent diamond, the 'Western Star'. She, in fact, decides to wear it at a party of the hostess who owns the companion jewel, the 'Eastern Star'. However, Marie's dream is short-lived as both the jewels get stolen before the event. Who is the jewel thief? Will Poirot's sharp mind get him the find?