The Mosaic Nipper is the recommended hand tool for cutting glass mosaic tile. This tool cuts glass up to 3/8-inch thick with minimal crushing and splintering, and it easily cuts molded tile into quarters, halves and triangles. It is also great for nipping up small pieces of stained glass, although it is not a scoring tool for making long straight cuts in stained glass. This is a compression tool similar to an ordinary tile nipper in the sense that you squeeze tile between the blades. Note that the circular blades do not actually rotate, although the blades should last for years if you don’t abuse them by attempting to cut materials other than glass.
You should not use ordinary tile nippers to cut glass tile. Ordinary tile nippers were made for glazed ceramic tile, and they tend to crush and splinter glass. For most artists, the mosaic glass cutters tend to pay for themselves in what they save in wasted tile.