Jeweler's saw blades designations run from 8/0 the finest to 14 to heaviest. What is right for the job depends on the thickness and hardness of the material, the intricacy of the pattern and the skill of the user. I would try starting out somewhere where the / numbers become single numbers. You are going to break a lot in the beginning so a few dozen in several sizes will help you find the right ones for you. I used the 4/0 size when cutting owner's initials out of lugs but that is probably too fine for beginners in most applications. I use heavier ones when hogging out blank areas. The general TPI sawing rule applies here too - 2 teeth should be on the work surface at all times. That is because if there is only one, the teeth will drop into the work and break off with motion.