Opal's Play of Color, Explained
The science behind opal's flashing rainbow—and how to compare stones.
Precious opal is made of tiny silica spheres stacked in neat rows. Light bending through those spheres creates the shifting flashes known as play of color.
Black opal shows the most vivid contrast, white opal looks soft and milky, and fire opal is prized for its warm orange body color.
Opal holds water and is relatively soft, so keep it away from heat, sudden temperature changes, and harsh cleaners.