THE SHORT ANSWER
A measurement can reject a bad match; it cannot certify a coin
Compare a coin's measured gross weight and diameter with the correct official specification. A material mismatch is a reason to stop and investigate. A match is only one screening result, not proof of gold content, authenticity, ownership or condition. The tool never supplies an invented Mint tolerance or turns two numbers into a green authenticity badge.
Eagle, Buffalo and Maple Leaf.
Two independent physical screens.
Never mislabeled as a Mint limit.
No automatic authenticity verdict.
MEASUREMENT WORKSHEET
Compare your readings with the correct official product
Select the exact product and size before measuring. Enter bare-coin readings only when removing packaging is appropriate. Optional tolerances are your own screening criteria and should account for device resolution, calibration and professional guidance. Leave them blank when you only want numerical differences.
Difference = measured value - published nominal value. The tool does not supply Mint manufacturing tolerances. Any tolerance is entered by the user and should reflect calibrated instrument uncertainty plus appropriate professional guidance.
Open the official specification source
A matching weight and diameter do not prove authenticity. A mismatch may also reflect the wrong year, finish, size, damaged coin, packaging, instrument error or an incorrect measurement method. Do not drill, file, cut, acid-test or otherwise damage a coin based on this worksheet.
VERIFIED PRESET TABLE
The same one-ounce label can describe different gross weights
| Coin | Fine gold | Fineness | Gross weight | Diameter | Source |
|---|---|---|---|---|---|
| American Gold Eagle 1 oz | 1 oz | 916.7 | 33.931 g | 32.7 mm | United States Mint |
| American Gold Eagle 1/2 oz | 0.5 oz | 916.7 | 16.966 g | 27 mm | United States Mint |
| American Gold Eagle 1/4 oz | 0.25 oz | 916.7 | 8.483 g | 22 mm | United States Mint |
| American Gold Eagle 1/10 oz | 0.1 oz | 916.7 | 3.393 g | 16.5 mm | United States Mint |
| American Gold Buffalo 1 oz | 1 oz | 999.9 | 31.103 g | 32.7 mm | United States Mint |
| Canadian Gold Maple Leaf 1 oz | 1 oz | 999.9 | 31.11 g | 30 mm | Royal Canadian Mint |
| Gold Britannia 1 oz | 1 oz | 999.9 | 31.21 g | 32.69 mm | The Royal Mint |
| Gold Sovereign Full Sovereign | 0.2354 oz | 916.67 | 7.98 g | 22.05 mm | The Royal Mint |
| Gold Krugerrand 1 oz | 1 oz | 916.67 | 33.93 g | 32.69 mm | South African Mint |
| Australian Gold Kangaroo 1 oz | 1 oz | 999.9 | 31.107 g | 32.6 mm | The Perth Mint |
The one-ounce Gold Eagle is heavier than a troy ounce because its 22-karat composition includes silver and copper in addition to one fine troy ounce of gold. The Gold Buffalo and Gold Maple Leaf are four-nines products whose gross weights sit much closer to the exact 31.1034768-gram troy-ounce conversion. Never compare an Eagle's gross weight with a Buffalo or Maple specification merely because all three contain one fine ounce.
MEASUREMENT DISCIPLINE
Instrument uncertainty belongs in the result
Use grams and millimeters. Troy ounces, ordinary ounces and pennyweights are not interchangeable.
A display rounded to 0.1 gram cannot support a claimed 0.001-gram conclusion.
Use suitable reference weights and follow the instrument manufacturer's instructions.
Re-seat the coin and repeat readings; note unstable or position-dependent measurements.
Calipers can mark soft gold or damage a proof surface. Never clamp aggressively across a design. A scale should be level, clean, stable and protected from drafts. Record whether packaging remains attached. If the coin cannot be safely removed, compare with a packaged-product specification or have a professional inspect it; do not subtract an assumed capsule weight.
WHY NO PASS BADGE?
Counterfeit screening is a chain of evidence
The U.S. Mint advises buyers to compare weight and diameter, inspect key features, understand current metal prices and premiums, and research the vendor. That sequence matters. A plausible weight does not show whether the interior metal matches the surface. A correct diameter does not prove the correct thickness or density. A convincing image does not show mass.
Continue to year-specific design, edge, security and counterparty checks.
Wrong product, packaging, damage, poor technique and counterfeit risk all remain possible.
Use reputable sellers and appropriate professional non-destructive methods.
No bargain compensates for an unverifiable seller or refusal to permit reasonable checks.
PRODUCT-SPECIFIC SECURITY
Use the feature set for the correct year and coin
Royal Canadian Mint documentation says Gold Maple Leaf coins dated 2014 and later can be authenticated by approved Bullion DNA dealers. The system uses the coin's micro-engraved security mark, specialized imaging and the Mint's secure database. A consumer phone photo is not the same process. The 2026 Maple also documents radial lines and a micro-mark bearing the final two digits of the issue year.
The redesigned one-ounce Gold Eagle includes a reeded-edge variation among its visible security details. The Gold Buffalo uses official inscriptions, weight, diameter and Fraser designs. Design changes can make a genuine older coin look different from a current reference, so identify type and year first. Do not use a single current image as a universal template.
SAFE NEXT STEPS
Investigate without destroying evidence or value
Do not drill, file, scrape, cut or acid-test a finished bullion coin based on an online checklist. Destructive methods can damage genuine metal, erase collector value and still produce ambiguous results when poorly performed. Likewise, improvised magnets, phone apps, sound recordings or density experiments should not be presented as conclusive.
- Pause settlement or preserve return rights when a discrepancy appears.
- Photograph the item, packaging, invoice and instrument displays without publishing sensitive serials.
- Confirm the exact official source for the year, size and finish.
- Repeat measurements with calibrated equipment and a documented method.
- Ask the seller which non-destructive verification methods support its guarantee.
- Use an experienced dealer, recognized grading service or qualified testing provider when value justifies it.
PRIMARY SOURCES
Official consumer-awareness, specification and security references
- U.S. Mint Bullion Consumer Awareness for vendor diligence, price scrutiny, specification and key-feature checks.
- U.S. Mint Bullion Coin Programs for current Gold Eagle and Gold Buffalo specifications.
- Royal Canadian Mint 2026 Gold Maple Leaf product sheet for the current one-ounce nominal specification.
- Royal Canadian Mint Bullion DNA for eligible years, security marks and approved dealer verification.
FREQUENTLY ASKED QUESTIONS
Gold coin measurement questions
Can weight and diameter prove that a gold coin is real?
No. They are screening measurements. A counterfeit can be engineered to match one or both dimensions, and a genuine coin can be measured incorrectly. Use the correct year and specification, calibrated instruments, documented security features, seller diligence and appropriate professional testing.
Why does the tool not provide an official tolerance?
The cited Mint product pages publish nominal specifications, not a universal acceptance band for every circulation condition, year, instrument or transaction. GoldObserve will not invent one. The optional tolerance fields are user-entered worksheet criteria, not Mint manufacturing tolerances.
Should I weigh a coin inside a capsule?
No, not when comparing with the published coin weight. A capsule, flip, label or assay card adds mass and can obstruct diameter measurement. Avoid removing packaging when doing so could damage the product, void a seller policy or destroy collector value; ask a professional to use an appropriate method.
Why is a one-ounce Gold Eagle heavier than a Gold Buffalo?
The Gold Eagle contains one fine troy ounce of gold plus silver and copper alloy, producing a 33.931-gram gross weight. The 99.99% Gold Buffalo contains the same fine gold with a 31.103-gram published gross weight.
Can I use a kitchen scale?
A kitchen scale may not have enough resolution or calibration for bullion screening. Record the device resolution, verify it with suitable calibration weights and do not treat a rounded display as a precise measurement.
What should I do if a measurement is outside my tolerance?
Stop and investigate before buying or altering the coin. Confirm the exact issue, remove any incorrect unit or packaging assumption, repeat the measurement with calibrated equipment, compare documented design features and escalate to a reputable dealer or qualified non-destructive testing service.