Cornflower blue, a shade of azure, is a shade of light blue with relatively little green compared to blue. This color was one of the favorites of the Dutch painter Johannes Vermeer, the other being yellow.

Cornflowers (Centaurea cyanus) are among the few "blue" flowers that are truly blue, most "blue" flowers being a darker blue-purple.

The most valuable blue sapphires are those that are cornflower blue, having a medium-dark violet-blue tone.

Robert Boyle reported a blue dye produced from the cornflower. This was also called Boyle's Blue and Cyan Blue. This dye color however, was not widely commercialized.

Cornflower blue is a Crayola color. It was originally introduced in 1949, in the box of 48 crayons.