[2] Watson arrives in 221B Baker Street where the page boy Billy shows him a wax effigy of Holmes placed near a curtained window in the sitting room.

When the Count decides to double-cross Holmes and takes the stone from his secret pocket to show Sam in window light, the detective springs from the chair in place of his replica and grabs the £100K jewel.

When tricked into insisting on arrest for whoever is found possessing the diamond, he finds the jewel in his pocket – where Holmes has placed it – and apologizes.

The Crown Diamond, subtitled An Evening with Sherlock Holmes, was first performed on 2 May 1921 at the Bristol Hippodrome, and was written before the short story, which was first published in October 1921.

[5] In the original play, the villain was Holmes's enemy Colonel Sebastian Moran of "The Adventure of the Empty House" infamy, not Count Negretto Sylvius.

[11] The most noticeable change is that Holmes does not feature except in the prologue and final scene (actor Jeremy Brett was away due to illness).

It is Mycroft Holmes (Charles Gray) who takes up the case of the stolen diamond, while Watson is retained to look into the Garrideb mystery.

The first aired on 2 December 1954 on the BBC Home Service and was dramatised by Felix Felton, with Ralph Truman as Count Negretto Sylvius.

The second aired on 4 September 1962 on the BBC Light Programme, and was dramatised by Michael Hardwick, with Francis de Wolff as Count Sylvius.