An opal is a mineraloid composed mostly of silica and water. Opals can express every colour in the visible spectrum, although the most common colours are white and/or green. They are also known to cause bad luck or misfortune to some people.
Madame Maxime was known to wear opals. While tidying up the cabinets next to the mantelpiece at 12 Grimmauld Place in 1995, Harry Potter came across a large blood-filled crystal bottle with a large opal set into the stopper. There was a cursed opal necklace for sale at Borgin and Burkes that Draco Malfoy purchased and gave to and Imperiused Katie Bell in an attempt to assassinate Albus Dumbledore.
- Harry Potter and the Chamber of Secrets (film) (Shortly seen in Borgin and Burkes)
- Harry Potter and the Goblet of Fire
- Harry Potter and the Order of the Phoenix
- Harry Potter and the Half-Blood Prince
- Harry Potter and the Half-Blood Prince (film)
- Harry Potter and the Half-Blood Prince (video game)