adjective

(of light or colour) very bright.

brilliant sunshine illuminated the scene

bright,shining,blazing,dazzling,light,vivid,intense,ablaze,beaming,gleaming,glaring,luminous,lustrous,luminescent,radiant,incandescent,phosphorescent,scintillating,resplendent,irradiant,lucent,effulgent,refulgent,fulgent,lucid,glistering,coruscating,lambent,fulgurant,fulgurating,fulgurous

noun

a diamond of brilliant cut.

an elegant necklace with four rows of brilliants