Kidney stone passed 2011-05-18. The scale card check pattern is made of 1/16 inch squares. While this isn't the largest stone I've passed, it was large enough to explain the aches and general discomfort felt over the last month or two.
Handheld Nikon D90, 50mm f/1.8 on a 12mm Kenko extension tube, lit with an LED ring light. Adjusted, white balanced to a whibal card, and cropped in Adobe Lightroom.