There are different ways to decipher Grey African parrot’s gender. To have valid and reliable results, the parrot should be beyond a year and a half.
The first technique: the eye.
The parrot should be calm and not scared or bothered.
Opt for a side look.
Male signs:
There is a small black triangle below the eye part, which is opposite the beak and the nose, as it is shown in the picture.
Female Sign :
There is no triangle in the female’s eye. However, there is a circle around the eye as shown in the picture.
2nd Technique: Tail Feathers
(Under tail feathers)
Male signs:
The tail is red till the end without any grey colour. The chest is all holy dark grey.
Female Sign :
The feather is red with variable grey edge. Its chest colour
changes gradually from dark grey to light one toward the stomach.
3rd Technique: Head & Beak Shape. 
Male Signs:
It has got a rectangular head and a bigger top beak.
Female Signs:
It has a round head and a thinner small beak.
Thanks to these techniques and to the help of Almighty, we can find out gender even if the absence of accurate materials such as Abdominal Laparoscopy and DNA.