An assay is used to analyze and verify the composition of precious metals, effectively certifying that the metal is as pure as claimed. Assayers often work independently of the refinery or mint, and they are used by many of the biggest private and official mints.

If your precious metal bar has gone through this process, then it will be accompanied by a card or a certificate. It may come in a sealed package with a visible assay card on display, as is the case with most of the bars produced by PAMP, or it may come with a separate assay certificate. Either way, this assay should display proof of purity, along with a unique serial number, which provides added authenticity.

Assays add extra value to precious metal bars, simply because they guarantee the purity and authenticity of the product. Because of this, they often carry a premium, and they are also easier to sell on.

History Of Assaying

Humans have been mining precious metals for thousands of years, and while testing and verifying the content of these metals may seem like a modern undertaking, assaying may have been around for more than two thousand years.

There is actually a passage on assaying in the Bible, seemingly referring to the fire method. More details on assaying begin to appear in European texts from around the 12th century, at which time the process of hallmarking also appeared in France.

In the United States, there has never actually been an official hallmarking scheme, but assaying has existed here throughout much of the country’s history. In the 1800s, gold prospectors sent their precious finds to assay offices in New York, Arkansas, Louisiana and Denver, to name just a few, and the oldest assay office was located at the Philadelphia Mint, which was first founded in 1792 and is still active today.

The Assaying Process

The type of metal being checked often dictates which assaying process will be used, but the product itself can also play a role. In all cases, the assaying process begins with the assayer taking a sample of the product. This is often done by taking a sample of the molten metal as it is being produced, but they can also take shavings of the cast metal.

From there, one of several techniques can be used to determine the quality of the metal:

  •         Wet: There are three types of wet assaying: volumetric, electrolytic and gravimetric. Silver is usually assayed via a volumetric method. This involves dissolving the sample in nitric acid before adding a salt solution. A white cloud then forms, and it is this cloud that is examined.
  •         Dry: In this process, chemicals are heated along with the sample, creating a waste material known as “slag”, which separates from the pure metals. These metals are then examined. Both gold and silver can be assayed using this technique.
  •         Fire: This is an old method, but it’s also a very destructive one. It is time-consuming, but it’s also accurate. During this process the sample is heated with fluxes and a carbon source, triggering a chemical reaction that creates separation and allows the assayer to determine the quality of the metal.
  •         Spectrograph: This process involves a light that is passed through the sample, with the assayer then examining the strength of this light to determine the metal’s purity.
  •         X-Ray Fluorescence: This technique is not as accurate as fire assaying, but it is much quicker and it is also non-destructive. The sample is irradiated, with the assayer then examining the x-ray beam it emits.

Where Will You Find Assay Cards/Certificates?

Assays typically come with bullion bars and they are common with all investment grade precious metals. This is because bars are often considerably bigger than coins, and they are often created by private companies, so that extra verification is welcomed by the investor. You may also get assays with special edition coins, commemorative coins and other high-value coins, although they are rarely included with bullion coins, where production numbers are high and authenticity is rarely an issue. In most cases, high-value coins will come with a Certificate of Authenticity.

Certificate Of Authenticity

Although similar, a Certificate of Authenticity, or COA, is not the same as an assay. It does serve to authenticate a product, but the process involved with creating a COA is not as thorough, and COAs, unlike assay cards, are rarely sealed with the product. Still, in the absence of an assay, a COA is the next best thing.

In some cases, gold and silver bullion will not come with an assay or a COA. However, providing the bullion has been produced by a reputable mint, one that is a member of the LBMA or is COMEX deliverable, then this should not be an issue. In fact, here at GoldBroker we occasionally sell bullion that does not come with assays or COAs, but we do ensure that everything we sell comes from a reputable, licensed mint, guaranteeing the authenticity of every individual product.

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