I covered my cake in pastel sequins (or those edible candies you use for cupcakes and such).  I then airbrushed a yellow shimmer over them to try to cover up some of the color.. like a primer.  Well, it didn't cover much so I let it sit and sprayed again with white.. still didn't cover.  I let it sit overnight and airbrushed it with gold luster spray and it still isn't covering.  I am so frustrated!! How to I get those things covered with gold?? Grrrr..... 

Paint them with a thick paint made with vodka and gold luster dust. 

I tried this just this week using the luster dust paint and it still didn't cover very well.  I went through 4 containers of it and I could still see the pastel color through.  I ended up using real spray paint because it was just a dummy for a fake photo shoot. I would be interested to hear how it is really done because I see these cakes everywhere and I have a real one on order in a couple months.

I tried some edible sprays over a PURPLE cake (it was sprayed with spray paint too, one of my friends did it for a display cake and said "who cares, I'm painting it" so it was REALLY purple. I was really surprised how well some of the sprays covered. I'll find the blog post, but i think it was the Chefmaster gold spray that covered the best. I bet it would cover the colors on those little discs really well, even if it took two coats. I was shocked at how well it covered the purple... Here's the link. I bet that the sprays have some kind of base in them that makes them more opaque than just using the luster dust. The PME pearl was the best coverage but I didn't have any PME gold to test. I bet it would be really good,though, based on the pearl (the pearl looked silver on the purple tier). The Chefmaster gold was really good too, the Duff gold was thinner and drippier. http://acaketorememberva.blogspot.com/2015/10/metallic-and-pearl-luster-sprays-review.html