Hi, I'm mostly just posting to follow as i'm interested in the answer. i would have guessed partridge but he seems fairly dark and i'm not good with colours on silkies. I suspect more photos of him standing up would be helpful for shape in terms of quality (as i think in chickens asking if they're pure means asking if they're good quality) along with checking his skin colour everywhere (any light toes/nails?) and number of toes. hope he turns out to be a sweetie for you!
I think every chicken loves a bit of TLC. He looks chocolate to me, but i don't know if that's a colour found in silkies- though a quick google shows some other images that look similar. You could see what happens when you breed him as i think chocolate is sex linked (though you'd need to breed a chocolate hen from his offspring to know). Otherwise, his comb, skin colour and number of toes all seem right for silkie.
Judging by this colour calculator, if he is chocolate and put to a black hen then you would get chocolate pullets and black cockerels as it is sex linked recessive not dominant. http://kippenjungle.nl/Overzicht.htm#kipcalculator if he isn't chocolate but a really dark partidge or gold birchen you will only get black chicks so that may help to tell. Good luck!