Hi,
If you mean glans, looking purple is OK, provided you do not have pain or irritation of any kind, since the area is generally kept covered by the foreskin. You have mentioned, you have not yet hit puberty, at the age of 15 if you have not started puberty, you should talk to your parents and discuss with a Pediatric Endocrynologist and get his advice.
Solace
Can you be more specific about where the purple coloration was? The glans can normally be a shade of purple, and the corona underneath is darker. The inner lining of the foreskin is mucous membrane, which is anywhere from pink to red.
that means it choking, go to the dr