When BSA introduced a new tank badge they usually colour matched some of them to the tank.
Usually this was only for a single season
There are 2 blue ones,
One has a pastel blue as shown in the catalogue page above and there was a darker blue.
Parts books only list the default red or black which you will see shown in the following years catalogue.
AFAIK here was a dark green one as well but I have only ever seen one bike wearing them which was a green shooting star .
When the new range was introduced for the 62 season BSA apparently did another run of colour matched tank badges, again for a single season.
It gets a little more confusing as some were silver and some were gold.
I had always believed that the silver ones were faded gold ones but having seen some NOS ones that were never fitted having the gold parts silver leads one to believe that they came both ways unless the gold is chemically unstable and fade to silver over time without the actions of sunlight.
We also must remember what is shown in the UK printed catalogues is always a painting and not a photo of the actual bikes.
This was common place at the time because printing from a painting / drawing was a lot cheaper than printing from a photo .
And the catalogue was often printed & distributed before a single bike it depicted had rolled off the line so what you see may or may not have been what BSA made .
USA printed catalogues OTOH are generally photos ( printing off photos must have been cheaper in the USA ) so are generally closer to the true appearance than a UK printed but again they were often taken using the pre production press bikes or proto types and again not actual production bikes so again there can be minor differences between what is shown & what was delivered.