Abstract: An apparatus and method for determining if a stone mounted in an electrically conductive mounting is a true diamond employs a housing to be held in one hand of a user while the other hand holds the mounting. An electrically and thermally conductive probe extends from the housing. The probe is held against the surface of the stone. Two assemblies connected to the probe measure sequentially to determine the thermal conductivity of the stone and the electrical conductivity of the stone. Displays indicate if the assemblies detect the high thermal conductivity of the stone consistent with diamond and the low electrical conductivity of the stone consistent with diamond. This apparatus distinguishes true diamond over such imitations as cubic zirconia with a lower thermal conductivity and moissanite with a higher electrical conductivity.

Abstract: An apparatus and method for directly indicating the gold content of a metal object employs a receptacle or cell into which is deposited a small portion of an electrolyte solution. The solution preferably contains copper and iron ions, acetic acid and hydrogen peroxide. At the bottom of the cell is a first electrode preferably of pure gold in contact with the solution. The first electrode is electrically connected to an electronic measuring and indicating apparatus. The metal object to be tested is connected by a metal spring clip to the electronic apparatus and then a portion of the object is immersed in the solution so that it forms the second electrode of an electrochemical cell. The electronic apparatus measures the voltage generated in the electrochemical cell after the voltage has stabilized and indicates by indicating apparatus the gold content of the metal object.

Abstract: An apparatus and method for directly indicating the gold content of a metal object employs a receptacle or cell into which is deposited a small portion of an electrolyte solution. The solution preferably contains copper and iron ions, acetic acid and hydrogen peroxide. At the bottom of the cell is a first electrode preferably of pure gold in contact with the solution. The first electrode is electrically connected to an electronic measuring and indicating apparatus. The metal object to be tested is connected by a metal spring clip to the electronic apparatus and then a portion of the object is immersed in the solution so that it forms the second electrode of an electrochemical cell. The electronic apparatus measures the voltage generated in the electrochemical cell after the voltage has stabilized and indicates by indicating apparatus the gold content of the metal object.