Estate Princess Cut Accented Platinum Engagement Ring CZ Center. This estate platinum engagement ring features a stair-stepped design down the shoulders with channel set princess cut diamonds at .70 carat total weight. These square diamonds have SI1-I1 clarity and G-H color. The 6.5mm round center is a cubic zirconia that can be changed out, or later upgraded, to a diamond of your choice by your jeweler. This estate engagement ring is a size 7 and weighs 7.65 grams.