We feel for /u/ChimkinLady. That sapphire gem chick, the one that rushes to the brooder door and perches on your arm, turning out to be a rooster is a special kind of heartbreak. It's the friendliest one, of course it is. The universe has a wicked sense of fowl play. You pick four pullets from the discount bin at Rural King, trust the sex link, and then you see that comb growing like it's on a mission. The white dot on the head was always there, just harder to spot when they were fluff balls. Now it's a neon sign.
The practical truth is harsh for city-zone keepers: if it's a roo, it has to go. You cannot negotiate with local ordinances, no matter how charming the bird is. That 10% error rate in sex-linked chicks is a real gamble. Most of us know the odds going in, but when you're standing in the store, the bin says "pullet," and you want those sapphire gems, you convince yourself the odds are in your favor. ChimkinLady is learning that lesson the hard way, and we've all been there. The comb and the growth rate are the dead giveaways at this age. If we were in her shoes, we'd start planning for rehoming now, before the crowing begins and the neighbors start asking polite questions.
What we would tell a reader who asked us about this exact situation is straightforward: enjoy those arm-perching moments while they last, but do not let your heart overrule your zoning laws. The white dot on the head in sapphire gems is a marker for sex-linked feather color, not a guarantee. The comb development is the real test, and at 2-3 weeks, a peacomb that aggressive is telling you everything you need to know. You can look for barring on the feathers as they come in, but by then the roo will likely be crowing. The friendliest bird is often the rooster candidate, because they are bold by nature. It hurts, but the kindest move is to find him a farm home where he can strut and crow without a city ordinance breathing down his neck. Start posting on local chicken groups today, not tomorrow. That sapphire gem deserves a future where his charms are a blessing, not a zoning violation.