Oops, I had told you some incorrect information. Friendships do not have 9 levels; that wouldn't make sense. They have between 6 and 8 ranks of "standingID" just to be confusing.
The "standingID" of friends should map to FACTION_BAR_COLORS, which is what I was thinking about in my first post. Not all the values of FACTION_BAR_COLORS will work obviously.
Update: Blizzard always defines friends as colour index 5, which is green, or FACTION_BAR_COLORS[5]. Look at lines 51-77 of
https://www.townlong-yak.com/framexm...utationBar.lua