While reading Jack Heuer's autobiography, "The Times of My Life", I came across this on page 66:

"Our modern range of wrist chronographs started in 1962 with these “Autavia”
models and continued in 1963 with the “Carrera” range. Both products
were very successful, and with every new production series we made
small technical improvements, for example by changing the shape of the
hour bars or the colour of the radium bars. In those years the manufacturers
of luminous paint were working hard to reduce the radioactive radium
content without drastically impairing the night-time legibility of a watch’s
numerals and hands, and this included trying out different colours including
yellow, white, orange and blue."

Is Jack suggesting that some of the lume used on the old Autavia's/Carrera's started off as maybe yellow or orange, instead of growing patina and settled to the color we see today?
Or did they all start off with white, and gradually changed color... as we commonly know for most vintage watches?

I ask because there's Monaco prototype with blue lume used. Could this be the same for earlier Autavia's/Carrera's from the 60's??