Water droplet on a CD surface

Apparently this is quite a common macro shot, but it's my first time doing it so I'm still excited by it! I set this up on my patio table last week, using natural light and just waving my hand about in front of the CD to create the different colours (I found this technique by accident when my son blocked the light with his hand whilst helping me position something!).

Camera/lens settings: ISO 100, f/16, 1/40s, 90mm, tripod.