Advanced Technologies for Analyzing Precious Metals

Optical emission spectrometry is a tried-and-tested analytical technique that is widely used to measure the elemental composition of metals and alloys. It is often referred to as spark OES, as electrical sparks are used to ablate surface material from metal samples so that it can produce characteristic optical emissions.

The ablated material is excited in the argon plasma generated by the sparks and a corresponding light in the UV-visible range is emitted. The emitted wavelengths are characteristic of each element, and their intensity is proportional to the element’s concentration in the sample. The light emitted is directed towards the optical system. The main component of the system, the diffraction grating, separates the polychromatic light into its monochromatic constituents by dispersion over a certain wavelength range. The photons of the wavelengths of interest are usually detected with PMTs (Photo-Multiplier Tubes) and transformed into electrical signals. Alternatively, the full spectrum or part of it may be collected with CCD detectors.

X-ray fluorescence (XRF) spectroscopy is a nondestructive analytical technique used to determine the elemental composition of materials. XRF analyzers work by measuring the fluorescent (or secondary) X-rays emitted from a sample getting irradiated by a primary X-ray source. Each of the elements present in a sample produces a set of characteristic fluorescent X-rays, like a fingerprint.  These fingerprints are distinct for each element, making XRF spectroscopy an excellent tool not only for qualitative analysis but also for quantitative measurements when processing the intensity of the emitted lines. 

Niton DXL and Niton XL2 precious metal analyzers are equipped with proprietary AuDIT gold-plating detection technology. Several independent, complementary algorithms in the AuDIT  software work in tandem to alert you to the probability that an item is plated, regardless of the gold concentration of the surface layer. 

AuDIT software alerts you when gold plating of up to 8µm is detected or suspected, warns you on low karat and non-standard karat measurement, and identifies the presence of nickel (Ni) generally used underneath gold plating. While limited to the thickness of gold typically used in jewelry and industry to plate items, the AuDIT technology detects plating for any non-gold substrate such as Vermeil (gold-plated silver), copper alloys, steel, tungsten, etc.