Brilliant comes from French brillant, 'shining', from Italian brillare, 'to sparkle'. It may ultimately trace to a Dravidian word for the beryl gemstone — one of the longest etymological journeys in English.
Exceptionally clever or talented; shining brightly with light or colour.
From French brillant, the present participle of briller meaning 'to shine', from Italian brillare meaning 'to sparkle, to glitter', of uncertain deeper origin. One theory connects it to Latin beryllus meaning 'beryl', a pale green gemstone that sparkles when cut, from Greek bḗryllos, ultimately from Prakrit veḷuriya, from a Dravidian source. If this derivation is correct, brilliant traces its ancestry through Greek, Sanskrit, and Dravidian languages — one of the longest etymological journeys
Brilliant may owe its existence to an Indian gemstone. One theory traces the word through French, Italian, Latin, and Greek all the way back to a Dravidian root for the beryl stone. If correct, every time you call someone brilliant, you are comparing their mind to the sparkle of a pale green mineral from southern India.