TREND GAME Twice as Nice Two-tone jewels are riding a new wave of popularity. Their appeal is apparent for value seekers who want more oomph than silver alone provides, while gold-kissed styles can also help lure back reluctant karat gold buyers. Meanwhile, there’s more to love in the look itself—a little warm and a little cool, depending on your metal combination—so be sure to double up on metal choices moving into fall.  (Top) Rocky Ridge Burst necklace in 14k gold vermeil and Argentium silver; $700; Amanda Hagerman, Washington, D.C.; 570-244-5809; amandahagermanjewelry.com (Below) Kallini cuff in silver and 18k yellow gold; $1,395; Hera Collection, Toronto; 866-934-1660; designsbyhera.com (Inset) Pebble earrings in oxidized sterling silver and 14k gold with 18 cts. t.w. moss chalcedony; $498; Nina Nguyen Designs, Lafayette, Colo.; 720-459-