Royal crowns are headpieces worn by royalty and other high-ranking individuals to signify their status. The two most common types of royal crowns are diadems and tiaras. A diadem is a type of crown that is typically made of metal and encrusted with jewels, while a tiara is a more ornate crown that is usually made of precious metals and stones. Both diadems and tiaras are symbols of power and authority, and are often used in ceremonies and other formal occasions.