Sometimes, no matter how hard we try, pictures do not show accurately the true colour of the cere.
As Aluz has expertly stated, female budgies do indeed have blue ceres, with a chalky appearance and with white prominently around the nostril area. When they are in breeding condition, it turns dark, crusty brown.
Males also have blue ceres, but their cere is deep, dark blue, with no white nostril rings and some pale blue around the nostrils when they are out of breeding condition.
It depends on which you see in real life. As mentioned, pictures sometimes do not accurately portray the true colours.
It sounds like now it is up to you to make that judgement at this point