What is the best method or technology to use in identifying counterfeit coins and precious metals bars? That’s one of the most-often-asked questions and one the ACEF’s Research Work Group set out to answer.
The Research Work Group, comprised of knowledgeable and experienced dealers, began by identifying methods and technologies in use today and then evaluating their usefulness and effectiveness by cost, ease of use, accuracy and reliability. In the chart below, also noted is whether the method is harmful to the coin or bar.
Prepared by ACEF Research Work Group
Visual Inspection
Method:
Use naked eye to detect irregularities, imperfections, discoloration, corrosion or other signs of counterfeiting.
Cost:
None
Ease of Use:
Good – Requires no equipment; expedient method of observing surface of bar or coin.
Accuracy:
Poor – Highly subjective; limited to visual detection of color differences, polishing, and poor imagery.
Reliability:
Poor – Does not identify inner contents; best used as a confirmatory method for other testing equipment results.
Destructive:
No
Precision Digital Scales
Method:
Weigh bar or coin and compare to its standardized weight.
Cost:
Varies – $16 to $4,000
Ease of Use:
Good – Minimal training; expedient method of identifying weight of coin or bar.
Accuracy:
Fair – More expensive scales are more sensitive and accurate.
Reliability:
Fair – Provides exact weight of coin or bar; other testing methods required to confirm metal type.
Destructive:
No
Digital Caliper
Method:
Measure the diameter and thickness of a coin or bar and compare to standardized specifications.
Cost:
Varies – $10 to $500
Ease of Use:
Good – Minimal training; expedient method of confirming dimensions of a coin or bar.
Accuracy:
Fair – More expensive calipers are more accurate.
Reliability:
Fair – Confirms standardized size of coin or bar; other testing methods required to confirm metal type.
Destructive:
No
Fisch Tester
Method:
Device is specifically designed to confirm dimension of coin. Pass coin through slot, place in recess of device, and place coin on tip of device.
Cost:
Fair – $219 – $337
Ease of Use:
Good – Minimal training; expedient method of confirming thickness, diameters, shape, and weight of coin.
Accuracy:
Fair – Minting defects or irregularities in genuine products can cause false positive.
Reliability:
Fair – Works only on Krugerrands, American Eagles, and Maple Leafs.
Destructive:
No
Dimension Template
Method:
Insert the coin or bar into a slot of the same shape and size of the standardized product.
Cost:
Good – $5 to $10
Ease of Use:
Good – Expedient method of confirming proper shape and size of coin or bar.
Accuracy:
Fair – Minting defects or irregularities in genuine products can cause false positive.
Reliability:
Fair – Matches size and shape of coin to standardized specifications (especially helpful to distinguish ¼ oz. and ½ oz. coins from each other); other testing methods required to confirm metal type.
Destructive:
No
Ping Test/Jewelers Hammer
Method:
Lightly strike coin or bar with hammer to create a “ping” noise (Silver – 6145 Hz. Gold – 4498 Hz.) lasting a duration of 1 to 2 seconds.
Cost:
Good – $6 to $20
Ease of Use:
Good – Minimal training required; expedient method of testing internal metal content of coin or bar.
Accuracy:
Fair – Detects lead and tungsten plugged bars; subjective tool without use of audio spectrum analyzer.
Reliability:
Fair – Best used as a confirmatory method for other testing equipment.
Destructive:
Fair – Could cause dings or scratches in coins; not a preferred testing method for numismatic items.
Magnet
Method:
Place neodynium magnet next to gold or silver, which are both diamagnetic. Authentic gold and silver coins will not stick or trail to magnet.
Cost:
Good – $3 to $20
Ease of Use:
Good – Minimal training required; expedient method of testing magnetism of gold or silver.
Accuracy:
Fair – Subjective tool; coins could stick or trail “slightly.”
Reliability:
Fair – Used for gold and silver only; might yield false positive due to slight sticking or trailing.
Destructive:
No
Fischer Sigmascope
Method:
Enter metal type and size, and then place probe onto coin or bar. If metal conductivity is within normal range, machine will “beep.” Generically referred to as eddy current tester.
Cost:
Fair – $6,000 to $15,000
Ease of Use:
Poor – Requires training on use and calibration.
Accuracy:
Good – In seconds, metal conductivity determined with precision; detects tungsten-filled gold coins or bars.
Reliability:
Fair – Conductivity device cannot penetrate through thick plastic or bars; fails to detect differences in some metal types (e.g., aluminum in gold).
Destructive:
No
Specific Gravity Test
Method:
Measures density of coin or small bar. Use a scale (accurate to 0.001g.); a small container, distilled water, a string, and the dry sample. Weigh the dry sample and record dry weight. Place the cup on the scale, add distilled water to the cup and use the tare function to reset the scale’s display to zero. Use string to submerge the sample into water and record wet weight. Sample should not touch any part of the cup. Divide the sample’s wet weight into its dry weight to find the specific gravity of the sample. Compare sample’s specific gravity to reference value (e.g., American Gold Eagle = 17.78).
Cost:
Fair – $112 to $2,000
Ease of Use:
Fair – Requires water, multiple tools, and some instruction.
Accuracy:
Fair – Slight variation from reference range, especially when measuring fractional coins; brings in level of subjectivity.
Reliability:
Fair – Lead-filled silver or tungsten-filled gold could cause false negative reading for counterfeit.
Destructive:
No
X-Ray Fluorescence (XRF)
Method:
X-ray of surface to confirm metal type and identify purity and trace elements commonly alloyed with gold.
Cost:
Poor – $17,000 to $50,000
Ease of Use:
Poor – Requires training on use and calibration; some states require registration and regulated use of device.
Accuracy:
Good – Confirms metal type and homogenous low purity of surface.
Reliability:
Fair – Gold only; limited in depth to surface of sample analyzed; effective in combination with ultrasound and ping test.
Destructive:
No
Handheld Ultrasound
Method:
Use ultrasound device to send sound waves through coin or bar to detect whether coin or bar has been “drilled and filled.”
Cost:
Fair – $325 to $500
Ease of Use:
Fair – Requires training on use and calibration.
Accuracy:
Good – Detects “plugged” counterfeits, beyond the capacity of XRF and eddy current tester.
Reliability:
Fair – Detects inclusions and bar thickness; expert-made counterfeits will not have voids.
Destructive:
No
Acid Test
Method:
Place a coin or bar on a tray and put a few drops of nitric acid on a gold or silver bar. Gold: No reaction means it’s real. Silver: red, brown, or green means it’s real. Any other color means it is fake.
Cost:
Good – $12 to $50
Ease of Use:
Fair – Requires training on safe use of nitric acid.
Accuracy:
Fair – Confirms genuineness of surface of coin or bar.
Reliability:
Fair – Gold or silver only; does not detect “plugged” bars or coins.
Destructive:
Poor – Corrosive to surface; not an option for numismatic coins.
PAMP Veriscan
Method:
Use an iPhone app to scan and authenticate PAMP bullion coins and bars.
Cost:
Free
Ease of Use:
Good – Once app is downloaded, expedient method of authenticating PAMP bullion coins.
Accuracy:
Good – Proprietary method of tracing product to source.
Reliability:
Fair – Not efficient for bulk processing of coins; does not scan every PAMP product; app can be glitchy.
Destructive:
No
SMI Micro Engraving Reader
Method:
Place decoding lens over Sunshine Mint product. The word “VALID” will appear if the micro-engraved feature is in focus.
Cost:
Good – $24.95
Ease of Use:
Good – Expedient method of authenticating Sunshine Mint products.
Accuracy:
Good – Proprietary method of tracing product to source.
Reliability:
Fair – Not efficient for bulk processing of coins; only works on Sunshine Mint products.
Destructive:
No
RCM DNA Cube
Method:
Plug into USB, insert coin into the device. Use application to take high resolution photo of coin that matches photo to image in RCM database.
Cost:
None – Available only to distributors and dealers registered as members of RCM DNA Program.
Ease of Use:
Fair – Requires training on connecting and using device.
Accuracy:
Good – Proprietary method of tracing product to source.
Reliability:
Fair – Not efficient for bulk processing of coins; only works on RCM products, and with newer products with Leaf Privy mark.
Destructive:
No
Sigma Metalytics (Original PMV)
Method:
Turn on device, make sure all metal is removed from the sensor and then click “Run/Cal.” Once you select the type of metal to be tested (using the arrows), the green ready light turns on. Then place the metal on the sensor and check to see whether the metal is within range (within the brackets). Works for Gold, Platinum, Palladium, and Rhodium. *Note: Wands must be attached for smaller coins (1/4 oz.).
Cost:
Fair – $900 – 1,800
Ease of Use:
Fair – Requires training on use and attachments.
Accuracy:
Good – Measures the bulk metal in a bullion bar or coin form and ensures that the metal matches the electrical current specification of that metal type.
Reliability:
Fair – Not efficient for bulk processing of coins; or large items, e.g., 100 oz. silver bar; reads the metal using electromagnetic waves, and reads through plating, capsules, sleeves, and enclosures.
Destructive:
No
Sigma Metalytics (PMV Pro)
Method:
Turn on the device and set the metal type and input the weight of the sample. Place the sample under the correct sensor (one for small coins on the right and one for large coins on the left). Wand is available for purchase but not required. There are two bars on the display. The first measures the resistivity of the bottom side of the sample about 1mm into the sample and the second measures resistivity through the entire sample. If within range, the arrows will be in the “green” and if both readings agree, there is likely no foreign material in the sample. It also shows the diameter, the thickness of the sample. It can calculate the density, and therefore, the correct volume by hitting the “measure”/”dim” button and selecting whether the sample is round or rectangular. A green line appears on the screen along with a light, which gives the range that the sample should fit within. Place the sample in between both the green light and the line, and if it fits, then it is correct density/volume.
Cost:
Fair – $1,958 – $2,864
Ease of Use:
Poor– Requires training on use, calibrations, attachments and product types.
Accuracy:
Very Good – Ability to measure different qualities (size, volume, density) using the electromagnetic technology.
Reliability:
Fair – Not efficient for bulk processing of coins or large items; not good for metal of odd shapes (i.e., not round or rectangular).
