If you are new to investing in precious metals, you may have seen the terms assay and purity used with some frequency. This will be in the context of a product sold in assay that has a listed purity. These are two related factors that help to determine the value of precious metals in addition to their weight and appearance. Understanding assay and purity is vital, regardless of whether you are an investor, collector, or refiner.
Understanding Assay in Precious Metals
Definition of Assay
Assays are technical processes used to determine the precise precious metal content of a given metal sample. They evaluate the metal and any impurities that may be alloyed with it.
Purpose of an Assay
An assay’s primary function is authenticating a precious metal and determining its quality or purity. It provides an authoritative measure of value for products made of gold, silver, platinum, and palladium. It is essential for the trade and valuation of precious metals, as it determines the purity of an item or product. You may see products sold in assay and with assay.
Types of Assays
There are numerous assay methods; each has its own strengths and is suited for different purposes.
- Fire Assay Known for its precision, fire assays involve melting the sample with lead oxide to separate impurities. Though highly accurate, it is destructive.
- Touchstone Test A less destructive method is the touchstone test, which involves rubbing the sample against a touchstone, leaving a streak on the stone. After, the stone is treated with acid to reveal its purity.
- X-ray Fluorescence (XRF) Another non-destructive technique uses X-rays to identify the purity and composition of a sample.
- Ultrasound Assay Using ultrasonic waves, this assay detects inconsistencies in the metal’s structure and is great for bullion verification.
- Electronic Testing: Measuring the electrical resistivity helps detect whether a metal is solid or plated.
Purity in Precious Metals
Definition of Purity
Purity is a measure of the specific proportions of a given precious metal that an item or product contains. This is usually expressed as a percentage of fineness in relation to other metals and elements present within the item or product.
Purity has a direct impact on the price of precious metals. Higher purity generally correlates to higher value since pure precious metals are often more desirable for investment purposes.
Measurement of Purity in Precious Metals
- Gold Jewelry: Generally expressed in karats (e.g., 24 karats = 99.9% pure gold).
- Investment Grade Gold, Silver, Platinum, and Palladium: These are measured in millesimal fineness for granular accuracy. For instance, gold with %.1 impurities may either be expressed as 99.9% or .999 fine. Gold that is .999 is the standard but some products by the Royal Canadian Mint have an astonishing .99999 gold fineness.
Key Differences Between Assay and Purity in Precious Metals
Focus
- Assay: Measures specific precious metal content and composition.
- Purity: Indicates the ratio of pure precious metal to other elements and substances.
Measurement Units
- Assay: Results can be qualitative or quantitative.
- Purity: Expressed in millesimal fineness.
Applications
- Assays are used in refining, mining, and hallmarking.
- Purity is critical for pricing and quality assurance in jewelry and bullion markets.
Importance in the Precious Metals Industry
Jewelry
Assays confirm the metal content for hallmarking, which enables consumer trust in gold and silver jewelry. Purity standards like 14-karat or 18-karat gold impact pricing and consumer preference.
Investment
Comprehensive assays and purity measurements are paramount for accurately assessing the value of precious metals. Investors rely on these metrics to ensure honest and fair pricing.
Mining and Refining
Mining companies use assays to evaluate the quality of ore, while refiners depend on purity tests to certify the output of gold, silver, and other precious metals.
