Tyrphanax said:

Perhaps they flicker through slight changes in colour depending on lighting or angle-of-view?

Exactly. The 3M material did that as far as i know.

The added glow was animation done frame by frame as far as i am aware through rotoscoping.

If you watch the 76 trailer you see that the prototype sabers a work in progress were white.

I always thought Luke's sword in Star Wars was White-Blue, more Solid Blue in Empire, and of course in Jedi he has that green one with a hilt like Obi's from star wars.