The Ninth Stone by Kylie Fitzpatrick

It is 1864 and a jewel thief is on the loose in London and is murdering his victims.

Orphan Sarah O’Reilly has disguised herself as a boy so that she can work as a typesetter in the offices of Septimus Harding’s newspaper, the London Mercury. Here she meets Lily Korechnya, a wealthy widow who writes a column for the newspaper under a pseudonym.

Lily has been engaged by Lady Cynthia Herbert to help catalogue her magnificent jewel collection. She is especially struck by several large gems that belong to the Maharaja of Benares, which Lady Herbert has promised to have made into a special charm. The gems include a fiery red diamond that seems to exert an unsettling influence over anyone who touches it.

Then two gruesome murders take place; first a customs officer at the docks and next a jeweller in Hatton Garden. Both were strangled in an unusual and distinct way. A local boy known as Holy Joe is blamed for the murders, but Sarah and Lily are not convinced that the police have the right man. The trail of the missing gems leads them to India, to ghosts, and the dangerous cult of the destroyer goddess Kali.