The size of the blade used in a jewelry saw depends on the number of teeth per inch. The more teeth, the finer the blade. Ive always been partial to a size 2 blade which works best with wire that is 16 to 18 gauge. According to the chart in my Rio Grande catalog, blade sizes 2-5 can be used for this size wire. Most of the time, I find that this gauge of wire makes a nice chain. Anything lower than 16 is too hard for my hands to bend, and anything higher than 18 is very soft. For a chain that will be soldered, its easier (for me) to work with gages 14 - 18.
There are numerous manufacturers of blades. Laser blades are considered a higher quality blade because they are more consistent in the size of the teeth. My personal preference is a brand called Herkules, which come from Germany. I have used cheapo blades before and have had to change them constantly because they break so quickly.
Continue onto the next page of this article for some Sawing Tips.