In Sherlock Holmes’s “The Adventure of the Mazarin Stone,” what is the stolen jewel called?

The stolen jewel in Sherlock Holmes’s “The Adventure of the Mazarin Stone” is called the Mazarin Stone.

The story was first published in 1921 and later included in The Case-Book of Sherlock Holmes. It concerns the disappearance of a famous diamond and an attempt to recover it before it can be sold. The jewel’s name supplies the story’s title and distinguishes it from the many fictional gems appearing elsewhere in Holmes’s adventures.

“The Adventure of the Mazarin Stone” is unusual in the original series because it is told in the third person rather than narrated by Dr Watson. It also includes a wax figure used as part of Holmes’s deception, a theatrical device that helps create the impression that the detective is physically present.

The Mazarin Stone should not be confused with the Agra treasure in The Sign of the Four or the Blue Carbuncle in another short story. Those are separate jewels in separate cases.