Gold Purity: What Do the Numbers 999, 750, 585 and 375 Mean?

What exactly does gold purity mean? It is a numerical value that directly determines the proportion of pure precious metal in a given alloy. Traditionally, this ratio is expressed in parts per thousand, meaning thousandths of the total material weight.

Thanks to this, you can easily determine the real value of a product. Completely pure gold is marked as 999.9/1,000 and represents the absolute foundation of investment gold, such as certified coins and bars.

In jewelry making, however, this 100% pure metal is almost never used, because it is naturally too soft and prone to scratches or other mechanical damage. To ensure that jewelry can withstand everyday wear, goldsmiths mix the precious metal with other elements, most often silver, copper, or palladium.

This creates much more durable alloys, whose exact purity is indicated by specific three-digit numbers stamped as a hallmark. When it comes to investment gold, it must meet a certain level of purity to be considered investment-grade, specifically a minimum of 995/1,000.

What Is Gold Purity and How Is It Measured 

Gold purity represents a key parameter that clearly indicates the content of pure precious metal in an alloy. It is commonly expressed in parts per thousand, meaning the number of parts of pure gold per 1,000 parts of total weight. A piece of jewelry marked 585 therefore contains exactly 58.5% pure gold, with the rest made up of other metals.

These additional metals are added intentionally, because 100% gold is too soft. In the past, the traditional karat system was widely used, where the purest form of gold has a value of 24 karats.

Conversion to parts per thousand is then ensured by a simple formula:

• Take the number of karats,
• divide it by 24,
• and then multiply the result by 1000. 

In the Czech Republic, an independent Assay Office oversees the fairness of the market. Its main role is the strict control of precious metals and their official marking. Experts examine each piece of jewelry, and if it meets all standards, they stamp it with a small official hallmark. This serves as undeniable proof of authenticity.

Thanks to this state supervision, customers have complete confidence in the true quality of their purchase. In stores, you will encounter different levels of purity that determine both durability and price. Here are the most common ones regularly certified by the authority:

• Pure investment gold marked as 999
• Luxury jewelry marked as 750
• The gold standard for everyday jewelry, 585
• Very affordable products with a purity of 375 

The choice of a specific value always depends on the intended use. While investors seek maximum purity to store their wealth, fashion enthusiasts often prefer harder alloys that can withstand the challenges of daily wear. 

Pure Gold – What Do 999 and 999.9 Mean 

Pure gold represents the peak of precious metal purity on the market. The numerical designation 999 means that the alloy contains exactly 99.9% pure gold. However, the most widely recognized global standard is the impressive purity of 999.9, which is the highest level achievable.

The hallmark on such a gold product clearly confirms 99.99% of absolutely pure metal and forms the solid foundation for all modern investment bars. You should always find this marking on a bar.

Another advantage of investment gold is that it is exempt from value added tax (VAT). To qualify, it must meet specific conditions. For example, VAT law clearly states that all traded investment bars must have a minimum purity of 995 in order to legally benefit from this tax exemption.

Although the law requires a minimum of 995, renowned global refineries predominantly produce pure gold with a purity of 999.9. Among the absolute elite are well-known Swiss producers such as Argor-Heraeus, PAMP, and Valcambi. By purchasing bars from these companies, investors gain a 100% guarantee of the highest possible purity of the precious metal they are buying.

Thanks to this level of purity, the value of an investment bar follows the price of gold on major global markets.

Gold Purity 585 – What It Is and Where It Is Used 

Gold purity 585 means that the alloy contains 58.5% pure metal and traditionally corresponds to 14 karats. Thanks to its excellent balance of hardness and price, it is the absolute standard in jewelry making.

Although 585 purity is very popular, jewelry is not considered investment gold. By law, it does not meet the minimum requirement for pure metal content, which is set at 995. As a result, jewelry is always subject to value added tax (VAT) when purchased.

You can easily verify the authenticity of a piece using a state hallmark. Every legally sold item carries a small Czech hallmark stamped by an independent authority. You will often clearly see the marking Au 585, which reliably guarantees the quality of the metal.

Overview of All Purity Levels – Table 

Why Purity Matters When Investing in Gold 

When buying precious metals, their purity plays an absolutely crucial role. Tax laws clearly state that favorable VAT exemption applies exclusively to certified bars with a minimum purity of 995. For example, gold jewelry never meets this threshold.

The absolute purity of the metal also ensures global liquidity. The highest-quality bars with a purity of 999.9 are easily accepted on global markets, including the strict London Bullion Market Association (LBMA). In addition, a simple rule applies: higher purity results in a significantly lower spread when selling (the difference between the buying and selling price).

Frequently Asked Questions