With all these hints to water and fish, and now the diamond plate with a blue background, it made me think of my aunt's aquarium. She's got this fish that she says is called a blue diamond. I looked it up on Wikipedia:
http://en.wikipedia.org/wiki/Discus_...lour_Varieties
The fish is a variation of the
Discus fish. Maybe the peices are going to be discs? This kinda fits with the idea of inner tubes that have been mentioned. They're the same shape!