Diamond Flywheel Great for Metalsmiths, Metal Working & Cutting Precious Metals. This is a new 130 diamond flywheel. It is precision manufactured for bright cutting gold and other precious metals. It is constructed with a high-grade industrial diamond chip. This is a delicate tool for professional jewelers. The shaft measures 4 mm (5/32") in diameter. It measures approximately 1 1/4" (32 mm) long.