Why should "Cushion Brilliant" be so important to you?
The vast majority of Cushions throughout the world are Modified Brilliant.
Modified Brilliants are cut with big "bellies", which do nothing to make your diamond more beautiful or more brilliant. You are in fact paying for extra and unnecessary weight you can't see when the diamond is mounted in your finished jewelry, and you shouldn't have to pay for it.
Much bigger look for your money - at least 15% larger than typical Cushions of the same weight. Significant cost savings - at least 15% lighter than a typical Cushion of the same dimensions.