There are a lot of mods that let you create diamonds, including the awesome Equivalent Exchange mod, but unfortunately all the ones I know of ruin the game, because they are unbalanced with vanilla minecraft. I was hoping someone could make a new block that is similar to a furnace, perhaps called a cubic press (which is one of the real-life machines that could make diamonds).
It would be crafted with four diamond blocks (on the sides) and four obsidian (in the corners).
Two create a diamond, you would place it and put in one charcoal, then the equivalent of 64 coal as fuel. Preferably it would not allow you to pull out the charcoal until it is done, and would save progress if you ran out of fuel. That way you could use lava buckets or wood, replaced every so often, rather than having to necessarily have 64 coal. The fuel could either burn at the same speed as in a furnace, or possibly faster.
Precisely because it requires so many diamonds (36), it would not be available until much later in the game. Any takers?
(Oh, and if there is something out there that does this already, in a balanced way, please, let me know.)
Hm... I like the basic idea, but COAL is put under pressure to make diamonds... So wouldn't you power it with charcoal and make diamonds with real coal?
It probably doesn't matter too much whether it's coal or charcoal put in there. What matters is that it's pure carbon. But it would be powered by anything you can put in a furnace, whether coal, wood or charcoal. You would just need the burning equivalent of 64 coal.