The Cere is blue in Males.That is the area where his nose holes are!
Budgies can easily besexed visually. If the budgie is over 6 months old, or sexually mature, then the cere (nostrils) on the male budgies will be dark blue and the females will be pale or tan-ish and may be crusty. The only way this will not work is if your budgie is a lutino or albino. Lutino and albino budgies will ahve a different color cere than a normal when sexually mature.