Buying products made in America is in style again. Which should increase the sale of what many consider America's finest gemstone - Montana sapphires. The best known Montana sapphire mine is Yogo Gulch, the state's only primary corundum source. Primary, meaning that a gem being mined is still embedded in the rock where it formed and that this rock is still in its original location. If that host rock had eroded fully or partly and its gem contents have been moved by water or rockslide to some other area, this new site is called a secondary source or "placer deposit." In recent years, most of the sapphires from Montana have been coming from secondary sources. The sapphires found in these secondary deposits are vastly different in color and character from those found at Yogo Gulch. Hence, gemologists now distinguish between Yogo and other Montana sapphires. Yogo Gulch was discovered about a century ago, on one of the gravel bars on the Missouri River near Helena, Montana, by gold prospectors who cared very little for the brightly colored pebbles they found. The first Yogo sapphires were found very near the original dike in which they formed roughly 50 million years ago. In 1900, Yogo sapphires exhibited at the Universal Exposition in Paris won a silver medal in competition against stellar stones from Kashmir and Ceylon. Those prizewinning Yogo sapphire stones were hand-chosen by owners of the Yogo Gulch mine, then in its first full year of production.