How old is it? Do you have any pictures that show the neck and feathers on the back? My buff orp started to get quite the comb and wattles around 12 weeks and I figured great, rooster. Well she laid an egg at 20 weeks and has laid on every day since (at 8 now, she's in the box laying #9 right now). 
My other buff orp I got at the same time is just now starting to grow her comb and wattles. 
If it is younger and hasn't grown the pointy neck feathers yet that it will if its a rooster, you can part the feathers and look at the shape of the new ones growing in usually. The boys have pretty shiny, pointy feathers growing in and the girls are obviously blunt and rounded. Same with the saddle feathers. I would guess that bird is between 13-18 weeks though so you should be able to see feathers growing or already grown.