Like all knives, Opinel can get get dull after use. Sharpening is inevitable. Fortunately, sharpening is a piece of cake when you use Opinel's sharpening products. Opinel’s natural sharpening stones come from the quarries in Lombardy, Italy. Since the 15th century these stones are known for their sharpening qualities. The constant and balanced presence of quartz and carbonates in the rock provide excellent sharpening results.