Kay Jewelers uses real diamonds. However, they are not held up to the same standards as some of Kay’s competitors. That explains why Kay tends to have more affordable diamond options. Companies like James Allen always sell GIA or AGS-certified diamonds. Kay, on the other hand, uses IGI certified diamonds. IGI has looser standards. As a whole, you can expect real diamonds from Kay, but they are not of the highest quality. For diamonds of exquisite quality and are also both conflict-free and sustainable, I recommend Brilliant Earth.