Very interesting thread,it would be beautiful to see these represented somehow. I sometimes describe music as shiny, but I'm not sure what exactly I mean. Examples of what I think is "shiny"-
Wild Healer- Gojira
Fortune Days- The Glitch Mob
Dust and Light- Krallice (but it's more of a gritty shiny, like some kinds of sandpaper?)
I don't usually have colors associated, the most I get is dark/light, or sometimes sunset colors (usually if it's lyrically themed that way)
I'm sure there are more, but I can't think of any others.