Abstract: A weighing system and method having stable measurement resolution for measuring gems and other light masses. The system includes circuitry for correcting errors in the measured value of the masses due to off-center placement on the system's holding pan. The weighing system uses a plurality of transducers about the pan to measure the weight of the mass, and includes circuitry for converting the transducer signals to signals having unknown frequencies. Circuitry is also provided for determining the unknown frequencies with an approximate stable or fixed resolution, despite wide variations in the unknown frequency. In a preferred embodiment, the number of cycles on the unknown frequency is counted and counting begins and ends of the rising edges of the unknown frequency signal. The determination of which unknown frequency edge ends the counting operation is made by monitoring a known frequency counter.

Abstract: Springs for use in a weighing system for measuring gems and other very light masses. A pan and sensor assembly is used in which the springs are sandwiched between the plates of the sensor assembly. The springs have a generally conic cross-section and include holes for releasing air pressure when the pan and sensor assembly is compressed. In a preferred embodiment, grooves are provided in the surface of the springs which allow the springs to compress, in a bellows or accordion-like fashion, substantially parallel to a central axis. One large spring or a plurality of springs may be used in a weighing system. The weighing system uses three or more transducers about the pan to measure the weight of the mass, and correlates the values measured by each transducer for a given mass, at given locations, to arrive at a true weight value for the mass in spite of its potentially off-center location on the system's holding pan.