4.11 Art Deco Round Brilliant Diamond Engagement Ring in Platinum.  This impressive Art Deco engagement ring features a 4.11 carat Round Brilliant cut natural diamond in platinum. The primary stone is GIA-Certified and has a very light yellow hue. This gorgeous diamond is eye clean and cut in beautiful Round Brilliant style for the highest level of fire and brilliance. The main diamond is prong set and accented by six .03 carat diamonds that decorate the shoulders of the platinum band. For an antique diamond engagement ring that checks all the boxes, this is the one you have been waiting for!