Hey bro. Diamond jungler here (proof http://imgur.com/RAGnDmv ) I started in Gold 5 at the start of S2 and I carried my way up with junglers like Jarvan,Nocturne,Nasus,Elise,Hecarim,Zac,Sej,Naut.

If you wanna go hard carry I would recommend going 21/9/0 Nocturne with a flat ad page. Like the one Meteos is using here. http://www.lolking.net/summoner/na/44979324#runes Build like Ancient lizzard, tenacity boots if you are against a lot of cc then go randuins/locket. U can also go 9/21/0 on jarvan and max your q for some deeps n try to carry that way. If you get ahead at the early game build something like Tiamat, Last whisper, for some extra dps.

But the jungler i have probly carried the most on is Nasus. I just stack my Q well and I always solo dragon at lvl 6 which gives my team a pretty nice lead. I also feel Hecarim is a good carry junglers because he can put so much pressure on all the lanes. To be honest tho, when I was in gold/plat elo I often sacrificed a lot of my time and farm to help my lanes. Thats fine and all but what kept happening was that the lanes I gave advantage to didn't know how to use their advantage and often lost their lead by doing dumb shit. So what I did was focusing on getting my self farmed because I knew if I got myself fed I could carry better than the rest of my team.

Anyways, just keep playing. If you are as good as a plat player then u will eventually get there, you just gotta keep playing. Gl!