Here's what the foreword to Keep It Simple https://arnoldsche.com/en/vergriffen/keep-it-simple/ https://archive.org/details/keepitsimpleearl0000essl/ says about the Platinum colour, also known as Snow White:

> Esslinger had been working with Steve Jobs since 1982 and was of paramount importance for the look of Apple products as an external designer -—as of 1983 also as Corporate Manager of Design. The start of collaboration between Steve Jobs and Hartmut Esslinger went from 1982 to 1983 with “Snow White,” a new color and design concept that was the base for all future Apple products. Besides specifying certain design aspects, the concept entailed introducing a new color. The dull “greige” of the industrial and corporate workplace was to be replaced by a broken white-called “Snow White" in the US. First used for the Apple llc, this white not only made the computer esthetically compatible with living rooms but also psychologically underpinned the user-friendly menu navigation. The new “Snow White” line worked up by Hartmut Esslinger was supposed to be launched with the Macintosh Computer—originally designed by Jerry Manock-but many reasons made this impossible. So the revised version could not be introduced until later: with the Macintosh SE.