brilliancy

noun

1. (countable, uncountable)A shining quality; brilliance.

   “The beauty and brilliancy of this insect are indescribable, and none but a naturalist can understand the intense excitement I experienced when I at length captured it.”

   “[…] to assist greatly in the consumption of the lamp, and to diminish the aqueous precipitations produced on the interior of the lantern glass, which has the effect of reducing more or less the brilliancy of the light.”

   “[H]is ideal of grandeur was a splendid façade, diffusing its brilliancy outward too, irradiating hospitality.”

2. (countable, uncountable)An act of being brilliant.

   “His brilliancy lay in combining old concepts from far-flung fields into a new idea.”

   “Surely it must have been his brilliancy that accounted for Vardon standing out as a stroke or two better than such a model of steadiness as J. H. Taylor[.]”

   “2013, Hannah Eichler, The Key to Brilliancy: How to Unlock Your Child's Genius”

3. (countable, uncountable)A spectacular and beautiful game of chess, generally featuring sacrificial attacks and unexpected moves.