Good variety of Polished Spheres in a variety of stones and sizes. Spheres are frequently produced in places where sophisticated equipment may not be readily available. Some softer materials (aragonite, calcite, anhydrite, etc.) are often hand polished resulting in flat spots, bulges or other unconfirmities. Spheres, with a few exceptions, are rarely calibrated to exact sizes. We, therefore, offer spheres in a size range measured in inches. For example a 1 to 1 1/4 inch sphere could measure between 25.4 and 31.75 millimeters. Millimeter dimensions given in parentheses are for reference ONLY and are not meant to convey exact measurements. A useful conversion tool is 1/4 inch = 6.35 millimeters.