(23880) Two diamond rings.AF.Stamped 750 and 18k. Ring size O and Q. 8.2gms. Fellows uses a Thermo Scientific Nitron Handheld XRF Analyser to test metals. This technology is limited to examining metal to a depth of approximately 8 microns. Fellows does not guarantee the standard of gold or platinum unless an item is hallmarked. Results from electronically tested items should only be used as a guide and with caution, as false readings are possible.