A good, solid, cast tin alloy prepolishing and polishing lap. This hard tin alloy allows the casting to be rigid enough to serve as a solid lap, without bonding to a baseplate or being excessively heavy. It provides sharper meets and higher speeds than are possible with laminated laps, and does so without the use of toxic metals such as lead and cadmium. The new BATT alloy is now used by hundreds of experienced and beginning gemcutters. Its casting and machining properties are superior to 95/5 solder and other tin alloys, and more importantly, performs better with oxide polishes. Being solid castings, finished on both sides, BATT laps are more versatile than the one-sided laminated laps.