Tiffany and Co. Ruby Diamond Engagement Ring in 18k Yellow Gold. This romantic Tiffany Co. engagement ring features a .30 carat red ruby and .45 carats of diamonds in radiant 18 karat yellow gold. The center ruby is prong set and haloed by eight (8) .03 carat diamonds. In a beautiful floral arrangement, the ruby center is accented by an additional fourteen (14) diamonds on the shoulders of the band. The collection of diamonds are colorless and bright, bringing some beautiful light reflection to the warmth of the 18 karat yellow gold. From the profile, a modern cathedral setting with a sleek yellow gold basket holds the center stones. A timeless Tiffany’s engagement ring in ruby and diamonds!