14K Yellow Gold Calibration Disc Gemoro Auracle AGT1 AGT2 Gold Testers Metal type: 14K Yellow Gold Metal color: Yellow Karat/purity: 14K Gauge/thickness: 26 ga (0.405mm) Diameter: 1/4" (6.4mm) Used to calibrate AGT1, AGT2, AGT3 and AGT-BLUE gold testers