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What is an Assay?

When collecting or selling bullion or coins, you may have noticed that some items come in an assay card, or are accompanied by a certificate of authenticity. In the bullion industry, the definition of assaying has two meanings. In precious metal refining, an assay process is a test procedure for measuring and analyzing the purity of a metal. This procedure includes determining its composition in ores, alloys, mineral deposits and precious metals. This way mints assure that the bullion meets its precious metal standards of content and purity.

Methods of Assaying

Assaying processes depend on the precious metal type and the particular piece that is being analyzed. Each assay starts with taking a rock or molten metal sample and continues with one of the following methods:

Destructive methods:

  • Fire Assaying – the oldest, most accurate, and destructive assay method. The sample is placed in a crucible and heated to find out the amounts of non-precious and precious metals. It’s a standard method for testing precious metal bullion in mints and refineries.
  • Dry Assaying – heating fluxes, special chemical cleaning agents, together with the sample, to let the precious metals separate, cool down and settle at the bottom.
  • Wet Assaying – dissolving the sample by using solvents and chemically analyzing the solution.

Non-Destructive methods:

  • Spectrograph Assaying – analyzing the intensity and strength of the light emitted by the sample when passing an electrical discharge through it.
  • X-Ray Fluorescence Assaying – identifying the precious metal and its purity by irradiating the sample with an X-ray beam. Analyzing the level of intensity of the X-rays emitted by the sample.

Other Assaying Methodssilver assaying through titration, gold assay by cupellation. Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) for assaying platinum.

Assay Types

Bullion pieces mostly arrive in assays as a special proof. Small bullion pieces are often sealed in assay cards which bear their date of creation and assay info. Larger bullion pieces usually come with an assay certificate which has a similar design and acts as a proof of authenticity and purity. Both assay cards and assay certificates assure the sellers and buyers that the bullion product is pure and legit.

What is a Certificate of Authenticity?

A COA (Certificate of Authenticity) is a sticker or a seal placed on a piece of paper or certificate. This Certificate of Authenticity seal is a warranty that the bullion coin or piece is authentic. Though, unlike an assay, a COA doesn’t guarantee a thorough process which certifies the exact purity of the piece. The COA also doesn’t seal the bullion like the assay card does.

However, the COA displays essential details, such as the approval and authenticity stamp, the mint mark, and purity, serving as a proof that the bullion item is genuine. Some precious metal pieces don’t come with COAs, like bullion offered in bulk, or they may come accompanied with an assay instead.

Assay products vs. COA products

Bullion bars ordinarily arrive with an assay proof because they are large, valuable, and have high purity. Limited or special coin releases, on the other hand, arrive with a certificate of authenticity which proves their genuineness. Sometimes, limited edition coins and special bar releases also come with an assay.  

Precious metal assaying is fundamental both for producing and selling bullion. Both assays and certificates of authenticity assure the buyer or owner that the precious metal item was minted according to the mint’s standards and requirements of precious metal purity and content.

NGC & PCGS Graded Coins | How To Sell Graded Coins

What are graded coins?

Do you know how certain coins acquire their market value and what is the specific factor that certifies their authenticity? Graded coins are highly appealing to both collectors and investors because their grading serves (such as NGC or PCGS) as a guarantee of their value and authenticity. The grading process determines the physical condition of the coin – the so-called “state of preservation”. Coin grading became a usual practice in the United States beginning in the mid-19th century when the US Mint issued the first collectible coins.  

Top Coin Grading Companies

The coin’s grade is the key factor that determines the value of the coin. This grade is a sum of aspects, sometimes subjective ones, which place the coin in a certain category. This authentication process is performed solely by specific authorities who have strong knowledge in appraising gold coins and silver coins – the coin grading companiesIn the US, there are three main tiers for the coin grading companies based on their reputation and reliability. All grading companies, except NGC, PCGS, and ANACS, are in the lowest tier of grading services because of their reputation that is built on inconsistencies in rating coins.

For this reason, these companies charge a lower premium than the three exceptions mentioned above. America’s Oldest Coin Authentication and Grading Service (ANACS) is the middle-tiered grading company, the oldest on the market (as the title says), with grading regarded as acceptable. The top-notch grading businesses with the highest and most trusted rates are the Numismatic Guaranty Corporation (NGC) and Professional Coin Grading Service (PCGS). But what’s the difference between NGC and PCGS?! 


Both NGC and PCGS have an impeccable reputation, which makes the coins graded by them highly valuable on the market. These companies use the Sheldon scale, according to which, the coins get a grade from “1” to “70”. Both companies adopted this coin grading scale since their establishment (1986 and 1987 accordingly). NGC and PCGS also offer free access to their online databases of certified coins and an online coin grading guide for self-assessing the coin’s grades. The condition, value, and urgency for processing the request determine the coins’ premiums.

Over the last decades, NGC and PCGS became worldwide leaders in grading coins, especially the Chinese bullion coins. However, despite their similarities, there are still differences between these two coin grading services. NGC is keener in sharing detailed information about its grading process. They show that each coin is separately authenticated and graded by two experts, and, in case these two won’t agree on the coin’s grade, a third coin expert steps in. Besides, NGC is the coin grading service of the Professional Numismatics Guild and the American Numismatic Association. However, feel confident that any of the two top grading companies is definitely worth your choice.

PCGS graded coins  NGC graded coins

Grading coins – is it worth it?

NGC coins or PCGS coins? Certainly Yes!

Why? Because NGC and PCGS designations certify and assure a higher numismatic value to your bullion coin. Graded coins become a guaranteed product and acquire the reputation of the grading company.

Are “First Strike” coins the very 1st coins?

The US Mint, just like most mints, does not issue first strike coins. It’s very hard to keep track of the exact order of manufactured coins during their striking. The “First Strike” designation (PCGS) certifies that the coins arrived for grading within the first 30 days of issue from the mint. NGC also used to apply the “First Strike” label, but it changed to “Early Releases”. Are first strike coins worth more? This designation is highly regarded among enthusiastic collectors. The label adds a higher premium to the coin’s initial market price. However, there is no proof that the “First Strike” or “Early Releases” coins will keep their value in time. 

Do you own a graded coin that you would like to sell or authenticate? Contact NYCBullion, and we will appraise with high accuracy any of the following coins, graded and nongraded: