Moonstone

The Moonstone (1868) is generally considered to be the first detective novel in the English language and also one of the best detective stories of all time.
Rachel Verinder, a young woman, inherits a large Indian diamond on her eighteenth birthday. It is a legacy from her uncle, a corrupt army officer who served in India. The diamond is of great religious significance as well as being extremely valuable and three Hindu priests have dedicated their lives to recovering it. Rachel's birthday is celebrated with a large party, whose guests include her cousin Franklin Blake. She wears the Moonstone on her dress that evening for all to see, including some Indian jugglers who have called at the house. That night, the diamond is stolen from Rachel's bedroom, and a period of turmoil, unhappiness, misunderstandings and ill-luck ensues. Told by a series of narratives from some of the main characters, the complex plot traces the subsequent efforts to identify the thief, trace the stone and maybe recover it.