diadem

diadem \DY-uh-dem\, noun:

1. A crown.
2. An ornamental headband worn (as by Eastern monarchs) as a badge of royalty.
3. Regal power; sovereignty; empire; -- considered as symbolized by the crown.
4. To adorn with a diadem; to crown.

On the far side of the cloister in the long, chapel-like room called the Treasure, she sits on her throne -- a small stiff gold figure robed in gold and covered with jewels and crowned with a golden diadem.
-- Hannah Green, Little Saint

The sky above is blue; the many clouds -- sun-drenched, gilded, lively -- have moved down, settled like a great diadem on the broad ring of the encircling mountains.
-- Milan Kundera, "Love's labour's lost", The Guardian, November 2, 2002

Dead and gone is the British Raj in India, that most glittering jewel in the diadem of Queen Victoria.
-- Jan Morris, "The Power Behind The Empire", Time Asia, August 12, 2002

Diadem derives from Greek diadema, "a band," from diadein, "to bind around," from dia, "through, across" + dein, "to bind."