In the center of the chamber, hurtling downward headfirst, was Saphira. Her jaws were open and from between them erupted a great tongue of flame, bright yellow and tinged with blue. 
 
Battle for Furthen Dur, Eragon

>  A molten-blue halo engulfed Saphira’s head, flashing through her gemlike scales until she sparkled gloriously and seemed to be lit from within.

Down the rushing mere wash, Eldest, pg 213

> A torrent of blue fire erupted from between Saphira’s jaws and bathed the left side of the Lethrblaka’s head in a ravening inferno hot enough to melt steel. 

Assault on Helgrind, Brisingr