{"id":11135,"date":"2025-05-15T08:00:37","date_gmt":"2025-05-15T08:00:37","guid":{"rendered":"https:\/\/www.thermofisher.com\/blog\/metals\/?p=11135"},"modified":"2025-09-05T20:32:50","modified_gmt":"2025-09-05T20:32:50","slug":"5-precious-metals-analysis-methods","status":"publish","type":"post","link":"https:\/\/www.thermofisher.com\/blog\/metals\/5-precious-metals-analysis-methods\/","title":{"rendered":"5 Precious Metals Analysis Methods"},"content":{"rendered":"

We\u2019ve previously written about the four primary precious metals — gold, silver, platinum, and palladium — and how it is important to verify the content of precious metals pieces in order to assess the correct value. Pawnbrokers, cash-for-gold operations, and jewelry stores who buy and sell gold and other precious metals must ensure that they know the exact composition of pieces not only so they can value the pieces correctly in the store, but so they don\u2019t run into the issues of overpaying the customer, or getting underpaid by the foundry<\/a> if the pieces will be melted down and recycled<\/a>.<\/p>\n

There are five main methods for analyzing precious metals.<\/p>\n

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  1. Scratch and Acid Test:<\/strong> \u00a0The first method is the scratch and acid test, in which one uses a touch stone to scratch the piece of jewelry or metal, and then you pour different types of acid to determine the karats. This method is often used, but it’s not very accurate.\u00a0 Not only that, you’re using hazardous acids that can burn your fingers. In this infographic, we\u2019ve outlined eight reasons one should not <\/strong>use acid to test jewelry<\/a>.<\/li>\n
  2. Gold Electronic Testers<\/strong>.\u00a0 These testers use the principle of electrical conductivity to determine the gold concentration but have low accuracy.<\/li>\n
  3. Fire Assay<\/strong>. Fire assay, sometimes known as cupellation, is considered the most precise method. Brittanica<\/a> defines cupellation as a \u201cseparation of gold or silver from impurities by melting the impure metal in a cupel (a flat, porous dish made of a refractory, or high-temperature-resistant, material) and then directing a blast of hot air on it in a special furnace.\u201d The problem with this method, however, is that it is a destructive method because you must melt the piece in order to determine the gold concentration.<\/li>\n
  4. Lab Analysis.<\/strong>\u00a0 There are laboratory methods with larger and expensive machines, but you must do extensive sample preparation. Larger, bench top analyzers provide unprecedented performance in terms of x-ray tube power, beam collimation, accuracy, and sample positioning. These analyzers, however, are not portable, and in general, require a higher level of operation skills than those of portable XRF analyzers<\/a>.<\/li>\n
  5. Portable XRF Analysis.<\/strong>\u00a0 And last but not least, there is portable x-ray florescence, where one can accurately measure up to 22 elements in one reading. \u00a0XRF\u00a0is a nondestructive testing technique<\/a>\u00a0that can analyze a metal sample in seconds with little to no need for sample preparation.\u00a0Portable XRF analyzers<\/a>\u00a0deliver fast, accurate elemental analysis and karat amounts in seconds. In fact, advances in handheld XRF technology have expanded to the point that today\u2019s analyzers are capable of distinguishing alloy grades that are nearly identical in composition to one another. And unlike the fire assay method, the testing is non-destructive to the piece \u2013 another benefit to jewelry industry.<\/li>\n<\/ol>\n

    Technology Characteristics<\/h2>\n

    With this many choices, it can get a bit confusing about which method is best for your application, so we\u2019ve listed out below some of the characteristics of each method so you can make a quick comparison.<\/p>\n

    \"Precious<\/p>\n

    Our scientists made a comparison in 2020 among all the analytical methods, and we concluded that if you need an accurate, fast, easy, non-destructive method for a reasonable price, portable XRF technology is one of the best possible solutions among all the techniques.<\/p>\n

    X-ray fluorescence (XRF) spectroscopy<\/a> 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.\u00a0 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.<\/p>\n

    There are exceptions, however.\u00a0 We\u2019ve outlined below when it is best to use, or not use, portable XRF analyzers:<\/p>\n

    \"when<\/p>\n

    Resources<\/h2>\n

    We\u2019ve gone into more details about precious metals and their testing methods in our webinar Not All that Glitters is Gold<\/a>. You can download the recording anytime and see a demo of the analysis in action.<\/p>\n