Propane/LOX Exhaust Color

Just a detail to fill out a fictional rocket description...

I've done some homework on rocket exhaust colors, but flame colors from
rocket engines seem to be complex. Like, kerosene introduced to a
combustion chamber as a vapor produces a nearly colorless flame (e.g.,
H2O2/kerosene engines), while kerosene/LOX in the F1 is a bright yellow
(with that characteristic black near the nozzle from the sooty turbine
exhaust).

So, what would be the color (if any) of a slightly fuel-rich
propane/LOX rocket with regenetive cooling and a propane-driven
expander cycle turbopump (the fuel and oxygen are both completely
vaporized upon entry to the reaction chamber)? A faint blue? Some
yellow toward the tip as incompletely burned fuel mixes with
atmospheric oxygen?

Mike Miller