The trillion, an existing triangle cut, represents just 5% of the global market. Some occur in nature, but to cut them involves a lot of wastage and the result often lacks brilliance.

Ayla ring by Marei, 18kt gold and black enamel, with 1.56ct marquise-cut white diamond, from $23,000. Marei. From Oscars night jewelry to April birthstones, right now, it's all about that most ...

Chopard Haute Joaillerie Collection platinum and triangle-cut diamond drop earrings (totaling 18.51 carats); price upon request, at Chopard boutiques, 800-246-7273. 12.

The new Ladies GraffStar is equipped with a self-winding movement housed in a 43mm white gold case, its bezel set with a mosaic design of trilliant and triangle cut diamonds.