The color changing thermo-sensitive beads change color with small temperature changes. They display yellows, greens, purples and more combinations of colors. The beads are light weight for their size.
I can make it in any size and in-between size you need. Please include your size in the comments to seller.
Here are more options http://www.etsy.com/shop/phoebestreasure/search?search_query=mood&search_type=user_shop_ttt_id_5126316&shopname=phoebestreasure
The manufacturer of most of the Mood beads on the market (they are called Mirage Beads) states that while the beads are very durable, they should not be submerged in water.