I'm going to show you (as best as I can) how to make light transmitting concrete. Google it, and you will be amazed at how beautiful it is! I was desperate to get my hands on some...but considering the cost, I decided to make some with stuff I already had around.
This material has the strange effect of looking shiny or sparkly...but it's dull concrete at the same time! It's very entertaining to show off or play around with.