There is a Bao Zhong jewelry in Shanghai, D refers to diamonds-diamond ct refers to the measurement unit of diamonds-carats; 1 carat is divided into 100 blocks, and each 1 block is 1, 1ct= 100. So the D 0. 154ct on your diamond ring means that the inlay on this jewelry is a diamond with a weight of 0.65438+. Only diamonds with more than 20 points have a grading certificate.