Identifying authentic medieval gold coins requires meticulous examination combined with historical knowledge. First, examine the coin’s weight and size. Medieval gold coins were minted to specific standards depending on the region and time period. The standard weight of a Byzantine solidus was about 4.5 grams, in contrast, the Florentine florin weighed roughly 3.5 grams. If the coin’s mass falls far outside accepted ranges, it’s likely a modern imitation.

Next, inspect the design and engraving. Authentic coins were struck by hand using dies, so they often show slight irregularities in alignment, depth, and detail. Modern fakes lack the organic imperfections of authentic hand-struck pieces. Check for signs of long-term handling and use. Authentic pieces show smooth, gradual erosion on raised elements like the monarch’s portrait or crown, while fakes may have artificially worn surfaces that look uneven or painted on.

Analyze the alloy used. The gold used in genuine medieval coins was highly refined, often exceeding 90% purity. Modern counterfeits may use lower purity gold or even gold-plated base metals. Scientific analysis using XRF or chemical testing verifies authenticity. But a simple magnet test can help rule out iron-based fakes since real gold is not magnetic.

Examine the inscribed legends. Inscriptions on authentic coins use period-appropriate Latin or vernacular alphabets with era-specific orthography. Be alert to incorrect letterforms, irregular spacing, or symbols that didn’t exist in the claimed period. If the typography matches a later century than the coin’s supposed date, it’s almost certainly counterfeit.

Evaluate the coin’s surface aging and corrosion. Genuine coins acquire a soft, uneven toning from centuries of burial or handling. Avoid coins with overly shiny surfaces or artificial coatings that look like they’ve been polished recently. Also, be wary of coins that appear too clean or lack any signs of soil or corrosion if they are claimed to have been unearthed.

Verify the coin’s history and origin. A coin with a traceable chain of custody from auction houses, museums, or academic digs is far more trustworthy. Be cautious of coins sold with vague origins or アンティーク コイン from unverified online sellers. Reputable dealers will provide certificates of authenticity and references to published catalogues.

Finally, consult experts. When in doubt, bring the coin to a trained numismatist or a curator focused on medieval currency. They can compare it to known examples and use specialized tools to detect modern minting techniques or alterations. Because authentic pieces are both rare and highly prized, thorough verification is a non-negotiable step in acquisition.