DEAR MISS MANNERS: I recollect that you cited only two occasions on which you can wear tiaras -- the opera and visiting with royalty.
Lately the subject has arisen in connection with a guest wearing her tiara to a wedding. Can you enlighten me on this pressing issue?
GENTLE READER: In theory, Miss Manners is all for the return of the tiara. Traditionally, ladies always "dressed" their hair, with jewels or flowers -- hence the surviving term "hairdressing."
So she will overcome her resistance to seeming flexible and add that she is amused and even mildly charmed by ladies who top off evening clothes with those lovely objects that have been neglected for decades. Indeed, she will add that some tiaras can be adapted to be worn below a chignon, to the side of a French twist, or as necklaces.
But even royalty doesn't wear tiaras on all occasions. Never to brunch, for example. And noblesse oblige requires not wearing a headdress that might seem to mimic that of the chief figure. So one may wear a tiara in the presence of a queen, but not an actual crown; and not a tiara in the presence of a bride who might use one to secure her veil.