tiara
noun [ C ] uk/tiˈɑː.rə/ us/tiˈer.ə/
（尤指女王等地位高的女性在非常正式的场合佩戴的）冕状宝石头饰
a piece of metal in the shape of half a circle decorated with jewels (= precious stones) that is worn on the head by a woman, especially a queen, etc., at very formal social occasions