Bleu celeste

Generally considered to be European rather than English or Scottish, after the First World War it started to appear in England in arms and badges relating to the Royal Air Force, though it is still doubtful if any more than a dozen examples could be found in British heraldry, and most British heralds consider it unheraldic.

While in the post-World War I period bleu-celeste is depicted as a darker shade, in prior times it was depicted as very light, and has even been treated as a metal, as azure charges have been placed on a bleu celeste field, and vice versa.

Regardless, bleu celeste is still used by heraldic authorities, such as Britain's College of Arms in London, with one example of the arms of Jacob Flamberg being granted in 2016 using bleu celeste in the blazon for the field, mantling and charge, in each case per pale/party with sable.

[2] In the arms of the University of Natal Athletic Union the azure is defined as "sky blue".

[3] In addition to bleu celeste, there is also an apparently unique example in British heraldry of the use of "light blue" in the Municipal Borough of Barnes, through which the Oxford versus Cambridge boat race passes on the Thames.