TREND GAME Pyramid Theme Triangular motifs are spilling over from fashion silhouettes into diamond shapes. Trillion-cut diamonds are showing up in traditional styles (think three-stone rings) and fashion-forward- looks alike, in both big and small proportions. The tri-pointed diamonds are understated and unexpected—and are growing in popularity. They’re the perfect choice for the collector looking to make a minimalist mark.  Top: Ring in 18k pink gold with 1.75 ct. emerald-cut diamond and 1.2 cts. t.w. trillion-cut diamonds, $20,745, Julez Bryant, San Diego, 760-931-1416, julez.com; stud earrings in 18k gold with 3.46 cts. trillion-cut diamonds, $51,480, Rahaminov Diamonds, Los Angeles, 800-742-8864, rahaminov.com; inset: Chloe Odette necklace in 18k pink gold with 0.94 ct. t.w. trillion-cut diamonds, $5,940, Melissa Kaye, NYC, 917-573-038