Use "de rigueur" in a sentence

1. The Aigrette: not quite a tiara yet and more formal than a jewelled head comb, is an underrated piece of jewellery that does not quite get the attention of it deserves.However much some may yearn the days where wearing tiaras was de rigueur for some formal occasion, the reality is that even in rarefied circles a woman will only wear one a few times in her life.