Alot of Thai silks don't have full blue coloration over their head, that's a fact, alot of them still have an uncolored line running down the middle of the forehead. Also a small percentage of males will develop a nice size kok, I don't know if that's specific to Thai silks genetics, but you seldom see males with those huge kamfa or even zz like koks.
Sent from my HTC Sensation using MonsterAquariaNetwork App