Gem of Sphene also known simply as Sphene, is a Notai ship which lives in the system behind the Ghost Gate. It sent one of its ancillaries to Athoek Station to determine the political situation of the Radch.
Sphene was captured by Athoek Station Security after the Undergarden was flooded by the collapse of the ponds in the station's gardens.
Breq convinced Governor Giarod of Athoek Station to ignore Sphene's status as an ancillary and to treat her as Radchaai. Sphene subsequently decided to become a member of Breq's household.
Spene is a member of the Provisional Republic of Two Systems.