Buckingham Palace released the royal cypher to be used by King Charles III. It employs the “Tudor” crown rather than the stylized version of the St. Edward’s Crown favored by his late mother, Elizabeth II. Her four predecessors used this Tudor style crown in their cyphers as well as on their coats of arms. This has led to the erroneous belief that there is a “Queen’s crown” and a “King’s crown” used heraldically in British royal heraldry. That is not the case. It is simply a matter of each sovereign’s personal preference.
EXARANDORUM 
Thank you Guy for addressing the Kings/Queens crown farago, it has been annoying me that so many supposedly well-informed commentators use such terms without even blinking. I note that the Tudor crown does not have the Koh-i-noor diamond, it will be interesting to see if the King’s choice of crown for his cypher prefigures some move to repatriate the diamond?
I think that’s doubtful. The Koh-i-noor is presently mounted in the crown that was made for Queen Elizabeth, the late consort of George VI and King Charles III’s grandmother. That crown is slated to be used to crown Queen Camilla at the upcoming coronation.