Traditionally, the word "tiara" refers to a high crown, often with the shape of a cylinder narrowed at its top, made of fabric or leather, and richly ornamented. It was used by the kings and emperors of some ancient peoples in Mesopotamia. The Assyrians used to include a pair of bull horns as a decoration and symbol of authority and a circle of short feathers surrounding the tiara's top. The Persian tiara was more similar to a truncated cone, without the horns and feathers but more jewels, and a conic-shaped tip at its top.
In modern times, however, a tiara is generally a semi-circular band, often metal, and decorated with jewels, which is worn as a form of adornment. It is worn by women around their head or on the forehead as a circlet on very formal or high social occasions. Tiaras are frequently used to "crown" the winners of beauty pageants. In western countries, a bride often wears a tiara as part of her bridal gown.
Queen Elizabeth II is said to have the largest and most valuable collection of tiaras in the world, many of which are heirlooms of the British Royal Family. She is often seen wearing them on state occasions. Her personal collection of tiaras is considered to be priceless; in addition she received many of them through inheritance, especially from Queen Alexandra, and gifts from foreign countries. For example, a diamond and aquamarine tiara she received was a present from the people of Brazil.