My daughter wants an Ice-Watch for her birthday but she has an allergy to nickel. a lot of watches use this in the backs or straps. I have taken a look at the one she wants (www.joshuajamesjewellery.co.uk/products/details/20490.html) but im not sure and its an awful lot of money to spend on something she may not be able to wear. has anyone got any advice on what I should do or if the backs of these watches are plastic ?