Comparing XRF Analysers for Precious Metals
We have previously written about the need to use XRF technology to confirm or identify gold and other precious metal content in jewellery, decorative pieces, coins, and other items. This time of year can bring the best out of people, but occasionally it brings out the worst, and we have warned jewellers, pawnbrokers, and gold buyers that they need to be aware of scams during the holiday season. We have noted scams involving fake gold bead necklaces, coins that don’t make the grade, bad Krugerrands, and gold-plated tungsten or other metal items presented as solid precious metal pieces.
We’ve also discussed the various verification tests that business use to combat these risks, including the scratch and acid test, which is widely used but not very accurate and potentially dangerous. The most precise method is fire assay, but this method destroys the sample – something you do not want to do with a piece of jewellery. Laboratory methods with expensive machines require extensive sample preparation. Finally, there are portable XRF analysers.
X-ray fluorescence spectroscopy (XRF) is a non-destructive analytical technique used to determine the elemental composition of materials. Handheld XRF analysers work by measuring the fluorescent (or secondary) X-rays emitted from a sample when excited by a primary X-ray source. Each of the elements present in a sample produces a set of characteristic fluorescent X-rays, or “unique fingerprints”. These “fingerprints” are distinct for each element, making handheld XRF analysis an excellent tool for quantitative and qualitative measurements of precious metals, as well as other metals and alloys.
There are different types of portable XRF analysers, depending on the need. For example, manufacturers may be worried about trace lead in consumer goods, carbon in steel pipes, or metals and alloys used in critical parts, while jewellery manufacturers are concerned about the accurate gold, silver, or platinum content. There are different XRF analysers that are best for different applications.
Since gold and precious metals are usually in demand this time of year, it is important that jewellery stores and pawn shops have the appropriate tool on hand to verify gold and precious metal content of their pieces – especially since some of these XRF instruments are equipped with proprietary gold-plating detection technology that can alert operators to the probability that an item is plated, regardless of the gold concentration of the plated surface layer. The latest technology works for vermeil (gold-plated silver), as well as gold-plated copper, steel, tungsten, and any other non-gold substrate. This is especially useful in the jewellery business.
Another characteristic to take into consideration is how it will be used. Does the operation need an instrument that can sit on a jewellery counter and show the customer that the precious metals content in their piece of jewellery that they are either buying or selling is verified right in front of them?