When I first started re-reading this tale for this review, the first thought that came to mind, as Billy ( imagine Charlie Chaplin ) was detailing the comings and goings of the individuals connected to the story, was one of the scenes in that wonderful comedy "Without a Clue". You know the scene; the one with the Prime Minister, the director of the Exchequer and Lestrade, where only one individual actually thinks Holmes (Watson in this case) should take on the job. One thinks he shouldn't and that he (Lestrade) is better qualified to do it, and one has no opinion at all.
The story takes place in only one room, with before unmentioned secret doors. The plot incorporates props (the wax bust, mention of an air gun, blackmail and murder of old women) from other stories as well as personalities. Even some of the wonderful Sherlockian quotes seem re-written and reused from other stories.
And the plot is also contrived from other tales.
And several noted Sherlockians would argue that Doyle (Watson) did not write the tale.
It would best be argued that Doyle was pressed for time at some publication date and resurrected "The Crown Diamond" for quick publication.
I doubt it ever made any one's top ten list.
You can, however, buy this wonderful copy at amazon for $450.00.