Ruby Knight cover illustration by Geoff Taylor

The Ruby Knight by David Eddings
The second book in the Elenium series 1990
Ehlana, queen of Elenia, clings to life by a thread preserved within a diamond-like block of crystal conjured by a sorceress with the aid of a dozen Pandion knights. For a year, their lives will save hers. However there is a lost jewel which will save her life, if it can be found.