The reason you get a blue light, is that there's no white LED's as such, since they are monochromatic lightsources (or very close). The most common way to create white light from a LED, is to make a blue or ultra violet LED and cover the inside of the lens with a phosphorous layer that converts the blue light to almost true white light.
Since this convertion isn't complete, you get a bluish light from those.
The other way to create "white" light from a LED is to put several (at least four) emitters (Red, Green, Blue and Yellow) onto a single chip or four chips into a single LED housing. Some of those have the wires from all the colours connected to the outside and are actually capable of producing a vast amount of different colour mixes - including what appears to be different grades of white - others have only two wires and are a fixed "white hue".
So until now, there's no true white LED's, but some appears to be.