Verifying the legitimacy of historic gold coins requires careful observation and a basic understanding of historical context. 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. Substantial discrepancies from established weights often suggest a contemporary fake.

Analyze the relief and engraving quality. Genuine coins display subtle flaws due to manual die striking, such as off-center strikes or uneven relief. Counterfeit coins often appear unnaturally crisp and identical. Observe how wear has naturally developed over time. Genuine coins will have natural wear on the high points of the design, such as the ruler’s face or アンティークコイン crown, counterfeits often display fake wear that appears inconsistent, scraped, or applied with paint.

Test the coin’s metallic content. Authentic medieval gold typically contained 90–98% fine gold. Modern counterfeits may use lower purity gold or even gold-plated base metals. Laboratory testing via X-ray fluorescence or fire assay provides definitive results. But a simple magnet test can help rule out iron-based fakes since real gold is not magnetic.

Analyze the text and epigraphy. Medieval coin legends adhere strictly to linguistic norms of their time, often in Latin with regional variations. Look for spelling errors, inconsistent letter shapes, or anachronistic symbols. For example, a coin claiming to be from the 12th century but bearing a 15th century style of lettering is likely fake.

Evaluate the coin’s surface aging and corrosion. Genuine coins acquire a soft, uneven toning from centuries of burial or handling. Steer clear of coins that gleam unnaturally or show signs of recent mechanical polishing. If a coin claims to be出土 but shows zero trace of earth, rust, or encrustation, it’s likely fabricated.

Research the provenance. 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 from unverified online sellers. Trusted vendors supply COAs and cite authoritative references like the Sylloge or MEC.

Finally, consult experts. When in doubt, bring the coin to a trained numismatist or a curator focused on medieval currency. They utilize advanced equipment to identify tool marks, machine impressions, or chemical treatments invisible to the naked eye. Because authentic pieces are both rare and highly prized, thorough verification is a non-negotiable step in acquisition.