When it comes to investments, real estate has ­nothing on jewelry these days. At ­Christie’s New York April Magnificent Jewels sale, this ­dazzling diamond cluster necklace fetched $2.4 million, when just a few years ago a collector purchased it from British jeweler Laurence Graff for $1.5 million. “If you buy with a discerning eye and you buy important stones, the return is always exciting,” says Rahul Kadakia, head of the jewelry department at Christie’s. The platinum and gold necklace is set with a graduated series of modified rectangular-cut, ­cushion-cut, and square-cut fancy yellow and light yellow diamonds. Its 13 GIA reports contributed to the hefty price hike, adds Kadakia. As did its timeless aesthetics: “In the 1970s or 10 years from now, it would still look classic.”More bedazzling sales on JCKonline.com:+ Falling for a 5 Carat Heart-Shape Orangy Pink Diamond+