At around 8 months old, according to the Related Link, but other links said that it occurs at about 3 to 4 months.
female ceres turn brown around 6 months of age
Mating and living in the same cage does not require both budgies to be the same age.
You have to wait about a year, once they are adults then you will be able to tell like the person below said the males have a deep blue above their beak (kinda like their nose) and the females have a dark crusty brown nose, almost like a brownish red. When they are babies their noses will be white. Also budgies will start loosing the lines on their heads when they are adults so yeah. So it all depends on the age of the budgie, so just be patient. :) good luck I had the same issue too when I got my budgie! :D From. echub As adults, male budgies have a blue cere (the part above the beak, where the nostrils are), and females have a tan cere. Immature budgies, however, are different: young males' ceres are a purple-pink colour, and young females' ceres are pale blue with white around the nostrils. Cere colour changes with maturity. (When a hen is in breeding condition, the cere further darkens to dark brown, sometimes appearing "crusty".) Exceptions to the above rule are albino, lutino, and "creamino" (pale yellow/cream) budgies, whose ceres often remain the same throughout life.
about to 10 to 20 years of age.
You can usually tell a male robin from a female robin because of the brightness of their colors. The male robin's chest and belly will be a bright orange (or burnt orange). The female's chest and belly area will be a duller orange (or burnt orange).
Most baby birds ceres will be light coloured and darken as they age and mature.
If you are buying them from a pet store, you can never be sure. But most breeders will start selling baby budgies after they are weaned. Some are only a few weeks old.
Budgies usually live to be 10 to 20. The world's oldest budgie lived to a ripe old age of 29!
Look at the rings on your budgies head. The closer they are to the cere, the younger it is, the farther up the rings go ( or the more they disappear / more plainness the is on its forehead ) on its head the older it is.
Stars are blue because of their age and temperature. Blue is an indication of a young HOT star, when reddish color means the star is aging
Ceres is pretty much the same age as most other objects in the solar system: about 4.6 billion years.
Not when it's older than a youngster. Young budgies have black eyes and they are less muscular than adult budgies. But when budgie is about six months old, it looks and behaves like adult, and it's age is impossible to define. Colour doesn't matter.