This is a glowstone well that has a diamond spawner hidden in the water, causing diamonds to spew out of the water and around the well. It's fairly easy to make- all you need is a well, a diamond, and MCEdit. I will allow it to be used on servers.
Check out my YouTube channel: http://www.youtube.com/user/ethanandasher
Tutorial on making this: http://www.youtube.com/watch?v=lqWI0ma4wXA