Precious Metal Purity Levels Explained

Precious metals have long been the backbone of industries that require durability, chemical stability, and value.

In the catalytic converter recycling industry, understanding precious metalpurity levels is a financial, operational, and trust-critical matter. Mistakes in evaluating purity can lead to significant losses, impact market value, and even erode buyer-seller relationships.

In this guide, we’ll break down everything you need to know about precious metals, from how purity is defined and classified to the most reliable testing methods. Whether you’re a catalytic converter recycler, auto dismantler, scrap buyer, or refiner, understanding purity levels ensures you get the most from your material.

What are precious metals?

A precious metal is a rare, naturally occurring metal that is valued for its durability, chemical stability, and economic worth. Unlike base metals, which are common and prone to corrosion, precious metals such as platinum, palladium, rhodium, gold, and silver resist tarnish and retain value over time.

These characteristics make them essential not only for industrial applications but also for investment purposes, such as bullion, coins, and high-purity bars.

Precious metals commonly found in recycling streams

In catalytic converter recycling and other industrial streams, the most common precious metals are:

• Platinum: Highly malleable and resistant to heat, making it ideal for catalytic reactions.
• Palladium: Key for emission control and increasingly valuable in automotive recycling.
• Rhodium: Rare and highly reflective; small amounts carry significant market value.
• Gold and Silver: Not found in converters but often present in gold-plated contacts or sensor materials. Pure gold and fine silver are frequently recovered in small amounts for bullion or investment-grade purposes.

Why precious metals matter in catalytic converters

Platinum, palladium, and rhodium enable the chemical reactions that reduce harmful emissions, and their scarcity drives the recycling market. For jewelers, refiners, and recyclers alike, accurately assessing these metals ensures the material’s durability, integrity, and economic worth.

Even trace amounts of precious metal content have a high market value because of their catalytic properties.

What are precious metalpurity levels?

Purity levels indicate the proportion of a pure metal within an alloy or mixture. Purity can be expressed in several ways:

• Percentage: The fraction of pure metal relative to the total mass.
• Parts-per-thousand or parts-per-million: Often used in laboratory assay results to measure trace metals.
• Fine metal content vs. total mass: Especially relevant for gold alloys, white gold, or yellow gold where alloying metals are added for strength and color.

Common purity expressions

Karat levels are widely used in gold jewelry, but less relevant for industrial recycling:

• 24k gold: 99.9% pure gold
• 18k gold: 75% gold content, alloyed with white metal or copper
• Fineness: Expressed as .999, .950, etc., indicating high purity

Other expressions include weight-based content for gold bars, silver coins, or bullion, often measured per troy ounce.

Why purity is not always obvious

Purity can be difficult to identify due to:

• Alloys and alloying metals that change color, hardness, and malleability
• Ceramic vs. metallic converter cores, which affect precious metal content
• Variability between manufacturers and model years, impacting precious metal content

Understanding these factors helps you avoid assumptions that could affect payouts.

How are precious metalpurity levels classified?

Purity levels are classified using industry-recognized standards to ensure accuracy, reliability, and market value consistency. Let’s take a look at a few.

Industry-recognized purity standards

• ISO standards: Provide measurement and sampling protocols.
• ASTM methods: Standardize laboratory assay practices.
• LBMA and refinery-grade benchmarks: Define high purity thresholds for bullion, fine gold, and pure platinum.

Refinery vs. field classification

In the recycling industry, preliminary grading often uses tools like X-ray fluorescence (XRF) guns, while final assays are conducted in certified labs. Most recyclers never deal in “absolute purity” upfront, because metal purity can vary within a batch.

Laboratories will often use X-ray fluorescence benchtop and inductive-coupled plasma (ICP) devices to get an accurate reading of each metal contained in catalyst material.

Purity vs. recoverable value

It’s important to remember that high purity levels don’t always translate to high returns. Many factors can affect your payouts, such as losses during refining or smelting, which can reduce recoverable precious metal content. Catalytic converter unit type, vehicle mileage, wear & tear are also factors to consider which can reduce available metal content.

That’s why accurate measurement, such as XRF benchtop and ICP devices are critical to get the accurate value of your material.

What methods are used to classify the purity levels of precious metals?

Now let’s get into the nitty gritty of purity levels: how are they classified. There are various ways that professionals go about this process, but let’s take a look at the most commonly used.

Visual and physical indicators

At a first glance, quite literally, there are a few signs of purity. While weight, density, and appearance are preliminary indicators, relying solely on them is risky. White gold, yellow gold, gold-plated items, or fine silver may visually resemble higher-grade materials but contain impurities.

Fire assay

The gold standard for accuracy, especially for gold alloys and bullion, is fire assay. It involves melting and separating metals to measure fine gold, platinum, or palladium precisely.

It’s extremely accurate but a destructive, time-consuming process that requires a significant amount of refining process. So what else do professionals count on?

X-ray fluorescence (XRF)

XRF benchtop machines are a rapid, non-destructive method. They use x-ray fluorescence to identify metal composition. Strengths include speed and preliminary grading, but it only analyzes surface material and may miss hidden alloying metals or impurities.

ICP methods

Inductively Coupled Plasma (ICP) analysis delivers lab-grade precision, detecting trace precious metals and supporting investment-grade evaluations. Essential for high purity platinum, palladium, and rhodium assessment. This is the platinum-standard method in the industry!

Wet chemical analysis

Acid digestion and chemical assay methods allow for precise quantification of metals, though accuracy depends heavily on operator skill. Often used for small, high-value batches like fine gold, gold coins, or white gold components.

How can I assess the purity levels of precious metals?

If you’re looking to evaluate material at your yard or business, it’s important to remember that the only way to get an accurate, true reading is with laboratory analysis. But there are some preliminary tests that can give you a good idea!

Field-level assessment

Tools like XRF guns, density scales, and visual inspection can help you perform initial evaluation but they don’t determine precise content and value. For catalytic converter cores, platinum, palladium, and rhodium content can only be precisely measured through lab testing.

Why should I send my material for lab testing?

Lab testing makes financial sense, especially for:

• Bulk lots, where precious metal content can significantly impact market value
• High-value small lots, such as fine gold, 24k gold, or rhodium samples

Understanding test results

Lab reports present metal purity in percentage, ppm, or parts gold/silver/platinum. Misinterpreting these can lead to over- or underpayment. Always verify:

• Purity of gold, silver content, and platinum content
• Corresponding karat levels for jewelry or coin lots
• Accuracy against previous assays for consistency

How to identify the purity of precious metals in catalytic converter recycling

When it comes to catalytic converters, defining the purity of the metals they contain can be a bit tricky. Let’s take a look at why.

Challenges unique to catalytic converters

Because converters aren’t created with the same and equal amount of precious metals, they start off their lives already different from each other. Also, no two converters live the same mileage, wear and tear, maintenance and care, and more. That means that precious metal content, and purity, will vary. Other factors to remember are:

• Mixed metals and substrates complicate assay results
• Coatings vs. bulk material affect metal purity
• OEM variance creates wide fluctuations in precious metal content

That’s why it’s important to send your material to a processor, so your converters get sampled and tested.

Why accurate purity assessment is critical in precious metals handling

Even small percentage errors can equate to significant dollar losses. Pricing volatility in palladium, platinum, rhodium, and fine gold amplifies mistakes, making accurate assay essential. Accurate reporting builds credibility among buyers, sellers, and refiners.

It’s also important to remember to take into consideration the proper documentation and traceability needed. It prevents disputes with the law and with your buyers, sellers, and refiners, ensuring smooth transactions.

Compliance and reporting

Always ensure that you’re working with a partner that respects proper testing methods and reporting. That’s because proper testing methods and reporting help meet:

• Environmental regulations
• Audit requirements
• Contractual obligations with refiners

Common myths and misconceptions about precious metal purity

In the precious metal industry, especially the precious metal recycling sector, myths and misconceptions aren’t rare. Here’s a few common myths that the industry faces, and why they’re not considered truths:

• “Higher weight means higher value”: Weight alone ignores metal purity and alloying metals.
• “All converters from the same model are identical”: OEM variations affect precious metal content.
• “XRF guns tell the full story”: Surface-level x-ray fluorescence can miss hidden impurities.
• “Purity guarantees payout”: Losses during refining affect market value.

Best practices for managing precious metal purity in recycling operations

Whether you’re working with catalytic converters, scrap metal, end-of-life vehicles, or other scrap, it’s always crucial to follow industry standards. Here’s a few best practices to help you get started:

• Work with trusted labs, machinery, and experts to measure precious metal content accurately
• Provide regular staff training to maintain expertise in metal purity evaluation
• Keep historical data for comparison to detect trends or anomalies in assay results

The future of precious metal purity testing

No one knows what the future of precious metal testing holds for certain. However, advances in analytical technology and AI-assisted methods promise higher speed and accuracy. Automation enables real-time purity of gold, palladium, and platinum measurements, increasing transparency and trust in recycling markets.

That’s why understanding precious metalpurity levels is essential for maximizing market value, avoiding costly mistakes, and maintaining credibility in the recycling industry. By mastering testing methods or working with a partner who’s an expert, recognizing karat levels, and following best practices, you can ensure that every piece of jewelry, catalytic converter, gold bar, or other relevant scrap is evaluated accurately.

Accurate metal purity assessment isn’t optional. It’s essential for financial, operational, and regulatory success. Discover the tools, labs, and expertise that help industry professionals measure platinum, palladium, rhodium, and other precious metals with confidence.

Learn how precious metals are evaluated in recycling by contacting one of PMR’s experts.