Subject: How does the 'all day' part of 'all day Indiglo' work?

I now have an "all day Indiglo" Timex watch. I understand how the "Indiglo"
part works; it's an electroluminescent panel that makes the green glow that
is also seen on watches that Timex labels just "Indiglo". The "all day
Indiglo" watches have a background whose color changes depending on the
incident angle of the illuminating light as well as the viewing direction,
and can range from gold to green to blue. This is apparently a passive
mechanism unlike the electroluminescent panel. My question is, through what
physical processes are they able to get this dependence of color on the two
angles I mentioned, and, in general, how does it work? Is it a diffraction
grating like a hologram, or something else? Thanks!

Re: How does the 'all day' part of 'all day Indiglo' work?