"Gabi" Tolkowski, cutter of the "Centenary" diamond (largest colorless, flawless modern cut diamond), and recognized expert on diamond cutting, had this to say about the modern brilliant cut diamond,

 
"Cut is what turns an opaque, dullish-gray pebble into a mirror of light.  In its ultimate form, a finely shaped diamond is a masterpiece of mathematics, its angels precisely drawn.  In a classic cut, each of the 58 facets is aligned in exact relationship to the others to achieve maximum beauty."

 
"This is the beauty seen across a dance floor or a dining room as a brilliant flash of light, alive with a rainbow of changing colors.  It's what sets the diamond apart as the paragon of gemstones.  It's what makes the diamond so special, so valued."