Etymology Borrowed from French brillant (late 17th century), present participle of the verb briller, from Italian brillare, possibly from Latin berillus, beryllus (“a beryl, gem, eyeglass”), from Ancient Greek βήρυλλος (bḗrullos, “beryl”). By surface analysis, French brill(er) + -i- + -ant.
1
Shining brightly.
the brilliant lights along the promenade
2
Of a colour Both bright and saturated.
butterflies with brilliant blue wings
3
Of a voice or sound Having a sharp, clear tone.
4
Of surpassing excellence; magnificent.
The actor's performance in the play was simply brilliant.
"Thing is," Anahita resumed, and then, faltering, "Mean to say, well, we just think it's great." — "You, she means," Mishal corrected. "We think you're, you know." — "Brilliant," Anahita said and dazzled the bewildered Chamcha with a smile. "Magic. You know. Extreme."1988, Salman Rushdie, chapter V, in The Satanic Verses, page 268:
Etymology Borrowed from French brillant (late 17th century), present participle of the verb briller, from Italian brillare, possibly from Latin berillus, beryllus (“a beryl, gem, eyeglass”), from Ancient Greek βήρυλλος (bḗrullos, “beryl”). By surface analysis, French brill(er) + -i- + -ant.
1
A finely cut gemstone, especially a diamond, cut in a particular form with numerous facets so as to maximize light return through the top (called "table") of the stone.
This snuffbox — on the hinge see brilliants shine.1717, Alexander Pope, The Basset-Table:
On the one, a plain massive band which matched the collar; on the other, a serpent; the tail reached nearly to the elbow, and the head rose a little from the wrist; the tongue of a ruby, the eyes of large brilliants.1834, L[etitia] E[lizabeth] L[andon], chapter XXII, in Francesca Carrara. […], volume I, London: Richard Bentley, […], (successor to Henry Colburn), →OCLC, page 257:
1 more example
"And the ring?" I asked, glancing at a remarkable brilliant which sparkled upon his finger.1891 [September], A[rthur] Conan Doyle, “Adventures of Sherlock Holmes. Adventure III.—A Case of Identity.”, in Geo[rge] Newnes, editor, The Strand Magazine: An Illustrated Monthly, volume II (July to December), number [9], London: […], page 248, column 2:
Etymology Borrowed from French brillant (late 17th century), present participle of the verb briller, from Italian brillare, possibly from Latin berillus, beryllus (“a beryl, gem, eyeglass”), from Ancient Greek βήρυλλος (bḗrullos, “beryl”). By surface analysis, French brill(er) + -i- + -ant.
1
To cut (a diamond) with many facets, to make it into a brilliant.
In short, the diamond owed more to being brillianted and polished, and well set, than to any intrinsic worth or solidity.1851, The Western Literary Messenger, page 256: