The pinnacle of cartridge design can be found in a Koetsu stone body. The body is machined from a block of high quality stone. Each block is carefully selected for natural grain and polished to a very fine finish. Internally, only the most tightly matched silver sheathed copper coils and cores are used. Rare platinum magnets allow the stone body cartridges to fully create the ethereal sound on which Koetsu has earned its reputation.