I paint my own fabric for clothes and am currently working with metallic paints. Here’s green:
The first picture is an area of somewhat dense paint and the second is the edge where the paint is much less thick. I think the multi-colored shards are what make it a metallic paint. I was able to compare to a green non-metallic paint made by the same manufacturer and those colorful bits are not present.
Here is purple, with much the same colorful pieces embedded in the background color:
And finally, silver, where the shards are really clear:
For comparison, here is the non-metallic green paint from the same manufacturer:
It does not appear to have the same colored bits in it, though you can see that it is made up of different colors.
The two paints look like this out of the jar, metallic on the left and non-metallic on the right:
I also looked at something called Edible Gold Glitter. The ingredients are gum arabic, mica, titanium dioxide, and yellow, red, and blue food coloring. Yum. The colorful bits in this look quite similar to the ones in the metallic paint, so I am guessing that the paint uses something like mica to achieve the metallic affect.
Finally, this got me interested in what actual gold looks like so I extracted some of the flakes from Goldschlager, supposedly real gold.
Hmm, looks like a bunch of mountainous brown stuff with tiny little bits of gold. Maybe those edible gold flakes in food/alcohol are mostly something that is not gold. Some sort of substrate to hold the microscopic gold?