Natural Stone Resources TRVSILVER1224H-5MEWC 12" x 24" 5cm Silver Honed Modern Edge Travertine Wall Cap. Natural Stone Resources is a premier importer & distributor of quality natural stones from around the world. Whether you're looking to add coping to your masonry walls, columns, landscape, steps, or pools, the Silver Travertine Modern Wall Cap is a beautiful choice. Includes a modern edge on both 24" sides.