What's the noun for brillance? Here's the word you're looking for.
brilliant
A finely cutgemstone, 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.
“Closer to the moon, the numbers of the stars dwindled for the brilliance of the light from the moon overrode it.”
“Mathias remembers being struck by the size and brilliance of the structure and, beyond it, the multiple walkways and pavilions arranged across the vast site.”
“Those of us who knew him remember, not only his brilliance in music, but someone who was intelligent, funny, complex and loyal.”