RIP little one.
To me it looks like a female...was the cere DEEP blue, or whitish blue before the change? If it was whitish blue, then I'd say female. But if it was deep blue then it could very well be a male that died of testicular cancer. From what I've read it can cause the cere to turn brown.
Honestly i cant really remember, the cere changed colour within the first few months of owning him and has been like that ever since. I did some research a while ago about sexing budgies and i remember reading somewhere that the ones that have alot of white pigment will be harder to sex because their ceres dont go blue like normal males, they go a light pinkish colour which led me to believe he was a male. Ive dug up an old photo that was taken around when i first got them, it shows the cere before it changed.
The females beak went crusty like i knew it would but the other ones beak never did that, plus she was very bossy towards him and he had more of a song like call wheras she just went crazy with her calls lol this also lead me to believe he was a boy. Idk. They did everything together tho, cuddled, ate, preened, drank.
Do their eye colour have anything to do with sexing? because her eyes have white around the black but his were just fully black? as u can see in the photo.
Also does anyone have an idea what mutation he may have been? i was thinking recessive pied?