Most beekeepers put a paint mark on each of their Queens once they’ve mated and settled down in a colony
Why?
it makes her easier to find when doing an inspection
you know if she’s not the Queen you saw last time
it reminds you how old she is

1 or 6 is White
2 or 7 is Yellow
3 or 8 is Red
4 or 9 is Green
5 or 0 is Blue