Diamond & Emerald Halo Engagement Ring in PlatinumDiamond Emerald Halo Engagement Ring in Platinum. This modern engagement ring features a . 50 carat diamond surrounded by a halo of emeralds. The center stone is bezel set and sits low to the finger while fifteen emeralds add a gorgeous contrast of color. Additional diamonds on the shoulder of the ring add another layer of sparkle to this wonderful and unique engagement ring.