Cushion Cut Sapphire w/ Diamond Halo Engagement Ring in 18kCushion Cut Sapphire w Diamond Halo Engagement Ring in 18k. This modern oval sapphire halo diamond engagement ring classic in its design The 1. 33 carat oval cut center sapphire is simply stunning with its navy blue tone and is full of life. The center stone is surrounded by a cluster of ten (10) old European cut diamonds which provide a stunning contrast of color. The total diamond weight is . 60 carats. The top of the mounting is finished in yellow