The Saxons system was
to use a particular facing colour for two regiments and to give one
regiment yellow buttons and the other one white. But in the case of
the facing colour, pale blue, three regiments used this. In the early
period this did not matter as Kurprincessen was a grenadier regiment
and all its ranks wore the mitre (white buttons) and it was easily
distinguishable from
Prinz Gotha Regiment,
which also had white buttons, but whose rankers all wore the
tricorne.
But between 1757 and
1761 Kurprincessen all were forced to wear the tricorne (the mitres
had been lost at Pirna), and then later in 1761 they were all given
lapels on their coats and bearskins. This created a problem
distinguishing grenadiers of Kurpincessen with those of Prinz Gotha.
The Saxon solution (in 1761) was to give the grenadiers of
Kurpincessen medium blue lapels and waistcoat while retaining pale
blue cuffs and turnbacks. Confused, I'm not surprised!