Retro Round Diamond Engagement Ring in 14K Yellow GoldRetro Round Diamond Engagement Ring in 14K Yellow Gold. This Retro engagement ring features a . 15 carat round brilliant cut diamond set in 14 karat white gold with the band finished in 14 karat yellow gold. The two toned design looks amazing with the strength of the fishtail prongs that extend down the basket. The small accent diamonds on the shoulders add a bit more to the bright sparkle of this darling engagement ring.