How does cutting affect gemstone value?

The quality of a gemstone cut really influences its value, mostly because it controls the final brilliance, enhances its colour saturation, and reduces that annoying look of windowing or extinction, those dark patches that can make the stone appear dull.

If the proportions are weak, light can escape through the back of the gem, leaving it without life, and that can press down the market value hard. Experienced cutters sometimes give up a noticeable share of the original carat weight from the rough crystal, just to reach near-perfect symmetry and optical steadiness. So even if it seems counterintuitive, a very well-cut two-carat gem will often fetch more money than a badly cut three-carat stone made from the same material.