Fashion is going natural—earth tones, safari-esque silhouettes, and military neutrals like khaki and olive. The most precious of gemstones is following suit as designers toast diamonds in all shades of natural brown, from pale champagne to deep cognac. With a savvier and more sophisticated buyer at the higher end, these brown stones—like their pink, blue, and yellow cousins—have found a new audience. Unlike the pastels, however, the color lends a certain warmth to jewelry. And unlike black diamonds, they offer a neutral color without sacrificing their "diamond-ness." These warm stones with the cool sparkle and hot cachet also mix well with various metals, allowing them to complement virtually any skin or hair tone. White gold or platinum cools them down, while yellow or pink gold makes the stones easy to wear for women looking for a warmer tone.