Size 4 Economy Saw Blades For Ring Sizing & Jewelry Repair. This is a new set of 144 economy saw blades. This is a good inexpensive blade for novices and hobbyists. These blades are the best jeweler tested blades for all metals, wood, plastic and more. They are less likely to break and wander when cutting for a straight cut. These saw blades are size 4. Each measures approximately 5 1/4" (133 mm) long.