@Solaz
Only 'awakened' fruits affect the surroundings unless the original ability does it already. Most (nearly all) powers only affect the owner's body or project a specific ability (noro noro and mero mero, for instance).
The only ones we've seen actually alter the surroundings outside the original scope of the powers have been Doflamingo's string and the mochi mochi powers, due to 'awakening'.
None of this has anything to do with my comment, though. Fire has no forseeable upper limit, while lava does. If lava gets hot enough, the rock will vaporize and it will no longer BE lava. So lava trumping fire made no sense at all. The hottest lava on Earth is 2100-2200 F, while the hottest fire ever produced (by man) was 4990 C (9014 F). That's a hell of a large difference in temperature, don't you think? Diamonds will be forcefully vaporized and transformed into carbon dioxide around 1400 F.
@mage_goo
Yeah... Because he totally looks like he's thinking about keeping his clothes at a certain temp, lol. I think I'm just gonna go with "It's magic", since it doesn't make sense.