• “1 oz” Coins: For 22k items, your “Weight” includes alloy, but net metal is exactly 1 troy oz.
• Historic Coins: Pre‑1933 U.S. gold or older European coins often have .900 fineness, yet remain popular bullion.
• Modern Bullion Bars: Typically .999–.9999 purity, each stamped with brand, weight, serial number, etc.
• Market Premiums: Availability, brand, collector interest, and demand can significantly affect premiums over spot.

Karat jewelry represents a unique intersection between investment‑grade precious metals and wearable art. Unlike bullion—which is valued solely for its high purity and weight—karat jewelry must balance gold content with durability, intricate design, and superior craftsmanship. This makes its valuation more complex, as both the metal’s intrinsic value and the aesthetic or brand premium come into play.

• Alloy Composition: The “karat” designation specifies the ratio of pure gold to the total alloy, based on a 24‑part system. For example:
  • 24K: Nearly 100% pure gold (rarely used in jewelry due to softness).
  • 18K: Approximately 75% gold, with the remaining 25% made up of metals like copper, silver, or palladium. This mix provides a good balance of beauty and durability.
  • 14K: Roughly 58.5% gold, combined with higher percentages of base metals to increase hardness and wear resistance—ideal for everyday jewelry.
  • 10K: Contains about 41.7% gold and is often used in more affordable pieces.
  These alloying metals not only adjust the color—producing yellow, rose, or white gold—but also significantly enhance the strength and longevity of the jewelry.
• Design, Craftsmanship & Finishing: Beyond the metal content, the overall value of jewelry is heavily influenced by its design and craftsmanship. Artistic detailing, innovative design techniques, and finishing methods (such as hand‑engraving or high‑polish treatments) can add substantial premium over the raw metal value. Reputable hallmarks and designer signatures also help confirm authenticity and boost collectible or resale value.
• Testing Considerations for Jewelry: While many of the tests used for bullion—such as acid tests, electronic conductivity measurements, and XRF—apply to karat jewelry, there are additional challenges:
  • Surface Plating & Soldering: Many jewelry items are gold‑plated or feature solder joints. A superficial test may only reveal the plating rather than the solid core. It is essential to file or scratch a discreet area to expose the underlying alloy.
  • Complex Shapes: Unlike flat bullion bars, jewelry pieces often have intricate shapes or set gemstones, which can interfere with tests like density or magnet checks. Multiple tests at different points are recommended to obtain a reliable reading.
  • Multi‑Method Approach: Because of these challenges, combining visual inspection, acid or electronic testing, and, when possible, non‑destructive methods (such as XRF) provides a more complete picture of the item’s true purity.
• Market Premiums and Trade Considerations: The price of karat jewelry is influenced by more than just its gold content. A well‑crafted piece can command a premium based on brand, design, and rarity. However, buyers should verify that hallmarks and test results match the purported karat. For example, a piece marked as 14K might in fact be gold‑filled or only partially solid gold if it fails a multi‑test verification. Confirming purity through chemical or electronic methods is essential before making a purchase.

In summary, understanding karat jewelry means appreciating both its intrinsic gold value and the added premium for design and artistry. A multi‑method testing approach—including visual, chemical, and electronic tests—ensures you accurately assess a piece’s true worth, helping you make confident, informed decisions whether you’re buying over the counter, as a collector, or as part of a side business.

Refining converts lower‑purity or mixed‑metal scrap into high‑purity bullion. Modern refineries employ a combination of traditional and advanced techniques, including:

• Smelting (Pyrometallurgy): Melts the material at high temperatures with fluxes to separate bulk impurities. Traditional cupellation and modern doré furnace operations concentrate precious metals, removing base metals and generating a semi‑refined product for further processing.
• Chemical Refining – Aqua Regia: Dissolves impure gold (or other PGMs) using a mixture of nitric and hydrochloric acids. The insoluble materials (e.g., silver chloride) are filtered out and the pure metal is precipitated, achieving purities of 99.95%–99.99%.
• Chemical Refining – Cyanidation: Mainly used for gold extraction from ores, cyanidation leaches gold into solution. The gold is then recovered by cementation or adsorption, followed by further refining. While highly efficient (90%+ recovery), it is typically followed by additional processes for final purity.
• Chlorination & Electrorefining: The Miller process (chlorination) uses chlorine gas to remove base metals from molten gold, yielding approximately 99.5% purity, while the Wohlwill electrorefining process further purifies gold to 99.99% by dissolving gold anodes in a chloride electrolyte and plating pure gold onto a cathode.

These methods are often used in sequence to optimize throughput and purity: smelting concentrates the metal, chemical processes dissolve and separate it, and electrorefining produces market‑ready high‑purity bullion.

Refined precious metals are held to strict purity standards established by industry bodies such as the LBMA, ASTM, and ISO. For example:

• Purity Standards: Gold is typically refined to at least 99.9% purity, silver to 99.9%, while platinum and palladium are commonly refined to 99.95%. LBMA’s Good Delivery specifications ensure large bars meet or exceed these thresholds.
• Assay Methods: Refineries use a range of techniques to verify purity:
  • Fire Assay: The gold standard for precise measurement, involving melting and cupellation to isolate precious metals.
  • X‑Ray Fluorescence (XRF): A non‑destructive method that rapidly measures surface composition.
  • ICP‑OES/ICP‑MS: Advanced laboratory methods that offer multi‑element analysis with high accuracy.
  • Acid Tests & Density Checks: Quick, on‑site tests used for initial screening of metal content.

Regulatory bodies such as LBMA, ASTM (e.g., ASTM B562 for gold, ASTM B413 for silver), and ISO (e.g., ISO 24018 for 1kg gold bars) help standardize these processes and ensure that assay results are consistent and trustworthy.

Refiners recover precious metals from a variety of scrap sources – such as jewelry filings, dental scrap, electronic waste, and catalytic converters – and calculate payouts based on the net recoverable metal.

• Scrap Sources: Mixed scrap is pre‑sorted to separate different alloys. Each type (e.g., 14k gold jewelry vs. dental gold) is processed to maximize precious metal extraction.
• Melt Loss & Fees: Even under optimal conditions, a small percentage of metal may be lost due to process inefficiencies or retained in slag. Refiners typically deduct a standard percentage (often around 1–2%) as their fee or for process losses.
• Payout Calculations: The final payment is based on the assayed fine metal content after deductions, ensuring that clients receive compensation for the full value of the recoverable precious metal.

Understanding these details helps ensure transparency in transactions and that you’re paid fairly for the material submitted for refining.

Modern precious metals refining is not only about achieving high purity; it’s also evolving to be more efficient and sustainable. Key innovations include:

• Automation & AI: Robotics and advanced process controls optimize operating conditions, reduce human error, and improve safety and throughput.
• Advanced Chemical Techniques: Innovations such as biodiesel‑based solvents for gold recovery and non‑cyanide leaching (e.g., thiosulfate) are reducing the environmental impact of refining.
• Continuous Electrorefining: New cell designs (with rotating or vibrating cathodes) improve current efficiency and metal recovery, reducing energy consumption.
• Recycling & Closed‑Loop Systems: Cutting‑edge refineries recycle acids, water, and other reagents, achieving near‑zero liquid discharge and reducing waste while recovering additional metals from slag and dust.
• Sustainable Sourcing & Certification: Programs by organizations like the LBMA require refiners to adhere to environmental and ethical standards, ensuring responsible production throughout the supply chain.

These advancements not only enhance metal recovery and purity but also significantly reduce the environmental footprint of refining operations.

When buying gold or other precious metals, ensuring authenticity and accurate purity is paramount. A combination of tests helps you verify that you’re getting genuine metal. Below is a comprehensive guide that explains the science behind each method, practical usage tips, and strategies to mitigate risk and maximize profit.

1. Visual Inspection with a Loupe

The Science Behind It: A jeweler’s loupe (usually 10x magnification) lets you inspect an item for clear hallmark stamps and quality engravings. Genuine gold items have consistent markings (such as “10K”, “14K”, “585”, or “750”) and display the expected color and heft. Although the “feel” or perceived density is subjective and develops with experience, it remains a valuable initial indicator.

Practical Application: Begin with a visual examination. Use your loupe to find hallmarks in inconspicuous areas (like the inside of a ring or the back of a pendant). Note any signs of plating, uneven finishes, or inconsistent markings.

Benefits: Quick, non‑destructive, and low‑cost. Limitations: Cannot confirm purity alone; counterfeiters can mimic markings. Rely on experience and use this test as a first step.

2. Magnet Test (Including the Magnet Slide Test)

The Science Behind It: Gold and silver are non‑magnetic. A strong neodymium magnet will not attract real gold, whereas ferromagnetic base metals (like iron or nickel) will be drawn to the magnet. The magnet slide test uses eddy currents: when a magnet is slid down a non‑magnetic surface against a genuine gold or silver item, the induced eddy currents create a magnetic counter force that slows the magnet’s slide.

Practical Application: Bring a strong magnet close to the item. If it sticks, the item likely contains non‑gold metals. For flat coins or bars, perform a slide test by gently sliding the magnet down a smooth surface; a slow, controlled descent suggests the proper conductivity of genuine metal.

Benefits: Fast, non‑destructive, and inexpensive. Limitations: Non‑magnetic counterfeits (e.g., brass, copper, or tungsten‑based items) will pass a simple magnet test, so the slide test is important for further verification.

3. Stone and Acid Scratch Test

The Science Behind It: This classic method depends on the chemical reactivity of metals. A small amount of gold is rubbed onto a dark testing stone. Acid solutions, calibrated for specific karats, are then applied. Pure gold is inert and resists the acid, whereas alloy metals in lower‑karat gold react and dissolve.

Practical Application: Lightly file an inconspicuous spot on the item to expose the true metal. Rub the item on a touchstone to leave a streak, then apply drops of acid (starting with a weaker solution for 10K, then moving to 14K, etc.) to bracket the item’s true purity.

Benefits: Inexpensive and provides a qualitative measure of purity. Limitations: It’s slightly destructive (leaves a minor scratch) and requires careful handling of acids, which can degrade over time.

4. Electronic Conductivity Testing (Kee Gold Tester)

The Science Behind It: Electronic testers measure a metal’s electrical conductivity, which correlates with its alloy composition. A handheld probe applies a small electrical current; based on Ohm’s law, the resulting resistance indicates the metal’s purity. Gold, being highly conductive, shows characteristic readings that vary with karat.

Practical Application: After filing a small area to remove plating, place the probe on the item. The device quickly displays the karat value (e.g., 14K or 18K). It’s an ideal non‑destructive alternative to acid testing, especially for items where you want to avoid chemical exposure.

Benefits: Fast, non‑destructive, and ideal for routine checks. Limitations: Works best on gold and platinum only; it cannot test silver. Results can be skewed by surface plating if not properly prepared, and regular calibration is required.

5. X‑Ray Fluorescence (XRF) Analyzer

The Science Behind It: XRF analyzers emit high‑energy X‑rays that excite the atoms in a sample, causing them to emit secondary (fluorescent) X‑rays at characteristic energies. By measuring these energies and intensities, the device determines the elemental composition of the item.

Practical Application: Place the item on the analyzer’s window (or use a handheld unit) and run a scan, which typically takes about 30 seconds. The device then provides a breakdown of the percentages of gold, silver, copper, and other elements present, helping you confirm the item’s claimed purity.

Benefits: Highly accurate and non‑destructive; it provides a detailed composition analysis. Limitations: Only tests the surface (about 1 mm deep), so thick plating can mask the core material. XRF units are expensive and require proper calibration and training.

6. Sigma Metalytics Precious Metal Verifier (PMV)

The Science Behind It: The Sigma PMV uses a high‑frequency electromagnetic field to induce eddy currents within the item. It then measures the metal’s resistivity and compares the result to preset profiles (such as “Gold 22K” or “Sterling Silver”). This method assesses the bulk properties of the metal, rather than just the surface.

Practical Application: Place a coin or small bar on the sensor pad, select the appropriate preset, and let the device quickly indicate whether the item’s internal composition matches the expected profile.

Benefits: Fast and non‑destructive, it is particularly effective for detecting items with a fake core or inconsistent alloy. Limitations: It provides a pass/fail result without an exact purity value and requires the correct profile to be selected. It is best used in conjunction with other tests.

7. Specific Gravity (Density) Test

The Science Behind It: Based on Archimedes’ principle, this method measures density by comparing an item’s weight in air to its weight when submerged in water. Genuine gold has a known density (approximately 19.3 g/cc), so deviations can indicate a fake or a different metal.

Practical Application: Weigh the item in air, then submerge it in water and measure the apparent weight loss. Calculate the density and compare it to standard values for gold or silver. This method is most effective for uniform items like coins or bars.

Benefits: Non‑destructive and based on a fundamental physical property. Limitations: It requires precise measurements and a controlled setup. Items with complex shapes or inclusions (like stones) may give misleading results. Additionally, metals like tungsten have densities close to gold, so this test should be used alongside others.

8. Ping Test (Acoustic Resonance)

The Science Behind It: When struck, coins and bars vibrate at characteristic frequencies that depend on their density and elasticity. Gold and silver produce a clear, sustained ringing sound, whereas base metals tend to emit a dull thud.

Practical Application: Gently tap or “ping” the item—either manually or using a dedicated tester or smartphone app—to listen to its resonance. A genuine coin or bar should have a consistent tone that matches known standards for that metal.

Benefits: Quick, cost‑effective, and completely non‑destructive. Limitations: The test is somewhat subjective if relying solely on your ear. Ambient noise or minor differences in alloy composition may affect the sound. It is best used as an initial screening tool in combination with other methods.

Risk Mitigation & Profit Optimization Strategies

No single test is foolproof. Here’s how to integrate these methods effectively:

• Combine Tests: Use multiple tests (e.g., magnet + acid + electronic testing) to cover the limitations of each method.
• Prepare Surfaces: Always file or scratch an inconspicuous area to remove plating, ensuring you’re testing the underlying metal.
• Calibration and Maintenance: Regularly calibrate your electronic testers and replace acid or probe solutions as needed.
• Test Multiple Points: For items like chains or jewelry with several components, test various areas to detect inconsistencies.
• Educate Yourself: Build experience by comparing test results with known standards and reference charts, and consider using smartphone apps for quantitative analysis of acoustic or density tests.
• Document and Compare: Keep records of test results and reference data to ensure consistency and to make informed buying decisions.

By carefully integrating these methods, you can confidently verify the authenticity and purity of gold and other precious metals—ensuring you pay a fair price and avoid costly mistakes, whether you’re buying over the counter, collecting as a hobby, or pursuing a side business.

Platinum bullion coins are typically struck to a 99.95% purity standard and are legal tender with symbolic face values. Notable examples include:

• American Platinum Eagle (USA): Introduced in 1997 by the U.S. Mint, contains 1 troy oz of .9995 fine platinum. Available in multiple fractional sizes with a $100 face value.
• Canadian Platinum Maple Leaf (Canada): First issued in 1988 by the Royal Canadian Mint. Initially available in multiple denominations, now primarily a 1 oz coin in .9999 fine platinum.
• British Platinum Britannia (UK): Issued by The Royal Mint since 2017 with 1 oz of .9995 fine platinum and a £100 face value.
• Australian Platinum Koala (Australia): Launched in 1988 by the Perth Mint. Issued in fractional sizes and known for its collectible appeal.

Private refiners produce platinum bars in sizes ranging from 1 gram to 1 kilogram, typically at 99.95% purity. Leading products include:

• PAMP Suisse Bars: Known for the “Lady Fortuna” design and LBMA recognition.
• Credit Suisse/Valcambi Bars: Available in 1 oz and larger sizes, each with unique serial numbers and assay certificates.
• Other Refiners: Valcambi, Johnson Matthey, and others produce bars that meet industry standards.

Platinum’s bullion history includes early Russian platinum ruble coins and later modern issues that set the standard for purity. Highlights include:

• Russian Platinum Rubles: Minted from 1828 to 1845, these coins are now rare historical items.
• Isle of Man Platinum Noble: The first modern platinum bullion coin issued between 1983 and 1989.
• Other Issues: Occasional collectible issues from Austria and other mints.

Palladium coins are less common but follow a similar high‑purity standard (99.95%). Key examples include:

• American Palladium Eagle (USA): First issued in 2017, containing 1 troy oz of .9995 fine palladium with a $25 face value.
• Russian Palladium Ballerina: A historic series from 1989–1995, featuring annual ballerina designs and limited mintage.
• Canadian Palladium Maple Leaf (Canada): Issued intermittently since 2005, with a 1 troy oz coin in 99.95% palladium.

Palladium bars, typically produced at 99.95% purity, are offered in 1 oz and larger sizes by refiners such as PAMP Suisse and Valcambi.

• PAMP Suisse Palladium Bars: Available in weights from 1 gram to 10 oz, with assay certification.
• Credit Suisse/Valcambi Bars: Similar to their platinum offerings, these bars are 99.95% pure with serial numbers and assay cards.
• Other Sizes: Larger 10 oz and 1 kg bars are produced for institutional buyers.

Palladium’s bullion history includes early commemorative issues and limited‑run coins. Highlights include:

• Early Palladium Issues (1960s): Including the first palladium coins from Sierra Leone and Tonga.
• Soviet/Russian Commemoratives: Such as the 1988 coin celebrating 1000 years of Baptism of Kievan Rus.
• Limited Commemorative Issues: Occasional palladium coins from China, Australia, and Slovakia.