18kt yellow gold Vintage Hidalgo peach enamel 0.56ct diamond 'X' ring with diamond sides, size 7.5 (no sizing). Hidalgo Corp. was founded in 1983 in New York City by Silvio Hidalgo. The company specialized in beautiful 18k gold enamel rings, many of them stackable, set with diamonds and gemstones. These were originally three separate rings that have been soldered together to form one beautiful, wide band.