The Moonstone by Wilkie Collins

The Moonstone (1868) by Wilkie Collins is a 19th-century British epistolary novel, generally considered the first detective novel in the English language. The story The Moonstone was originally serialized in Charles Dickens' magazine All the Year Round. The Moonstone and The Woman in White are considered Wilkie Collins' best novels. Besides creating many of the ground rules of the detective novel, The Moonstone also reflected Wilkie Collins' enlightened social attitudes in his treatment of the Indians and the servants in the novel.
Rachel Verinder, a young Englishwoman, inherits a large Indian diamond on her eighteenth birthday. It is a legacy from her uncle, a corrupt British 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. The story The Moonstone incorporates elements of the legendary origins of the Hope Diamond (or perhaps the Orloff Diamond). Rachel's eighteenth 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. Later 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 of The Moonstone traces the subsequent efforts to explain the theft, identify the thief, trace the stone and recover it. (Summary by Wikipedia)