The orange is only somewhat accurate on partridge chicks that are over 8 weeks. I mis-sex at that age a lot. Interestingly, I haven't been wrong on one I sexed as a female at that age. Ones Ive thought were male turned out to be female.
All other colors are a guess unless you're used to chicks of a line and know how their comb and wattles develop at certain ages. Even then it isn't super accurate.
Chicks from good bloodlines in any other color can be very hard to sex. Sometimes taking until the bird lays at 9 months.