Too bad even Microsoft cannot keep the colors in sync on their own homepage.
Of the four logos on the first page, plus the "official print" (in jpeg, mind you) logo, each of them used different colors. The green was most apparent (of course) and it is easy to see the difference between the images, but even the other colors differ.
Must it be easy? Just define the kilogram as the mass of exactly (6.0221415*10^23/0.012) unbound carbon-12 atoms at rest and in their ground state  and at zero K, and let the future worry about the rest.