The British banned several industries in India to encourage the development of those industries in Britain. One of Gandhi's famous acts of disobedience was leading people down to the sea to make their own salt, an industry that was forbidden in India at the time.[1] The British did do a few good things for India, but they did some really bad things too.
The British rule in India was full of continuous exploitation of the Indian masses, both politically and economically. The value of freedom can't be measured in diamonds.
>What did Britain steal from India? Some diamonds, but most of the other stuff was renewable resources (and time/opportunity cost), right?
That's a sad, sick peace of imperial mentality. Would you rather be butchered by an army of some foreign people who consider people of their skin to be superior to yours, and then say it's only some diamonds?
What did the British steal from Native Americans? Only some gold?
What did the British steal from European colonists of America? Only some tea?
[1]http://en.wikipedia.org/wiki/Salt_March