On average, Sun Parakeets weigh approximately 110 g (4 oz) and are around 30 cm (12 in) long.They are sexually monomorphic.
Adults have a rich yellow crown, nape, mantle, lesser wing-coverts, tips of the greater wing-coverts, chest, and underwing-coverts. The face and belly are orange with red around the ears. The base of the greater wing-coverts, tertials, and base of the primaries are green, while the secondaries, tips of the primaries, and most of the primary coverts are dark blue. The tail is olive-green with a blue tip. From below, all the flight feathers are dark greyish. The bill is black. The legs and the bare eye-ring are grey, but the latter often fades to white in captivity (so using amount of grey or white in the eye-ring for determining "purity" of an individual can be misleading). It is easily confused with the closely related Jandaya Parakeet and Sulphur-breasted Parakeet, but the former has entirely green wing-coverts, mantle and vent, while the latter has green mottling to the mantle and less orange to the underparts. The Sun Parakeet is also superficially similar to the pale-billed Golden Parakeet.
Juvenile Sun Parakeets display a predominantly green plumage and resemble similar-aged Sulphur-breasted Parakeets. The distinctive yellow, orange, and reddish colouration on the back, abdomen, and head is attained with maturity.
Data refer: http://en.wikipedia.org/wiki/Sun_Conure