Review on BioSpec Smartphone Microscope Bead - 11079SMS by Ryan Olsen

Great product, what I was looking for. They're industrial quality, but you can find good ones by rolling them over a piece of glass or mirror that's on a slight incline. The good ones roll straight and smooth, the odd ones bounce, wobble or go sideways. There are thousands of patterns, and about one in 20 will be the quality of the lens. Beautiful clear pearls.