The metal in the 2015 collection is 316L stainless steel so is water resistant. However, leather chords or any other non-metal materials should be kept away from water so as not to result in damage to the material.
The metals used in this collection are mainly brass and tin, discolouration may occur from contact with liquids and moisture over time. This will only appear on the surface that comes in direct contact with liquids such as sweat on your skin. Avoid contact with water or any other liquids (i.e. perfume) as much as you can to minimize the damage.