- His pale, blue eyes
- The fast, black horse
- My four, funny parakeets
All of these examples are overpunctuated, meaning the commas aren’t necessary.
When it’s being dropped in the middle of a selection of adjectives, you can think of a comma as a replacement for the word and. If you wouldn’t insert the word and between two adjectives, then you wouldn’t put a comma there, either. Try reading the examples that way — his pale and blue eyes, the fast and black horse, etc. Sounds kinda clunky, right?
Another way of looking at this is that in the first example, the adjectives form a progression. Pale comes before blue and eyes because it modifies all the words that follow, or in this case both words; there’s no limit to how long a progression of adjectives can stretch. (One wonders if a progression of adjectives is related to a pod of whales or a murder of crows.) On the other hand, blue modifies eyes but not pale, and so it takes its place between them.
If a group of adjectives forms a progressing series, then again, there’s no need for a comma, any more than there would be between the final adjective and the noun. And everyone knows that “his pale, blue, eyes” is really wrong, right?
Sorry for the rant. Hopefully it’s helpful, though.