U.P. Base Ring (Half/Flat Version)To begin your beautiful custom ring set, start with our Half Flat U. P. Base Ring. Available in 14 karat white, yellow, or rose gold. Designed with a beautiful stone finish so it stands out from your other bands. Refer to FAQs for our ring size guide. Important Note: If you plan to create a stackable set, we highly recommend ordering your base top ring at the same time as your Half U. P. Base Ring. Given all bands are custom and made to order,