Another great feature from the 1.8 update that many of you might already know is that you can make the beacon light a certain colour by placed stained glass on top of it. But there's something you might not know...
When you place more than one piece of stained glass on it, the colours blend! So red and blue stained glass will give a purple light, and blue and yellow will give a green light. This could make any beacon rainbow even more amazing by blending each of the colours even more thoroughly.