Vintage Mid-Century Engagement Ring w/ Sapphire and DiamondsVintage Mid Century Engagement Ring w Sapphire and Diamonds. This original vintage Mid Century engagement ring features a 1. 45 round cut sapphire in the center. The center stone is accented by baguette cut diamonds on each side that add a layer of sparkle with every turn of the hand. The mounting is finished in platinum and is a wonderful example of 1950s craftsmanship.