A gold coin dismissed by others as a likely replica and sold at public auction for just above $200 NZD of its supposed scrap metal value has now been confirmed to be a genuine Ancient Roman artifact issued during the reign of Tiberius Caesar nearly two millennia ago.

The aureus was the principal gold coin of Ancient Rome, struck in refined, nearly pure gold in the 1st century AD.

The discovery—one of New Zealand’s most significant numismatic finds in recent years, perhaps second only to the controversial New Zealand 50c coin struck with a Solomon Islands obverse—was made possible through the specialist expertise of Aventine, the New Zealand-based firm renown for coin and banknote rarities. 

Initially described as a tested 14kt gold coin of uncertain authenticity, set in a damaged bezel, the item was brought to our attention and flagged as potentially benefiting from further assessment. Aventine’s specialists soon identified that it had likely once formed part of a coin-set jewelry piece dating from the late 19th to the 20th century.

Luxury brands such as Tiffany and Bulgari crafted elaborate high-end pieces incorporating ancient coins around that time—though only the finest ones used Ancient Roman gold.

While metallurgical testing technology has advanced significantly in the 21st century, its effectiveness relies not only on the available equipment but also the correct contextual application of scientific understanding. Without both, the resulting data can often be misleading. 

Using a PMV Pro by Sigma Metalytics—although not designed for ancient coins—the extrapolated data analyzed by our research department revealed inconsistencies and supported what our numismatic specialists had noticed: the coin possessed a significantly higher gold purity than 14ct. 

This preliminary finding was followed by secondary X-ray fluorescence (XRF) testing, which confirmed a composition of 99.78% gold with trace elements of iron—findings consistent with results documented in Oxford University’s Understanding Roman Gold Coinage Inside Out.

Independent authentication was also provided by Chip Gruszczinski, one of our regular consultants and a globally recognized authority on Roman coinage, best known for authenticating the renowned “One-of-a-Kind Carausius Coin Find.”Gruszczinski confirmed the piece as a genuine gold aureus issued under Emperor Tiberius Caesar, valued at nearly $10,000 NZD. 

Now held in the Kleos Collection curated by Aventine, this coin highlights our proven expertise in identifying, valuing, and selling significant numismatic assets as well as our unique standing in the marketplace. 

If you’ve inherited or are managing an estate containing coins or banknotes—we recommend consulting Aventine. As New Zealand’s leading firm in rare numismatics, we offer our specialist expertise in both private treaty sales and global numismatics auctions. 

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