Counterfeit roubles worth more than Tsar's own mint.

Counterfeit roubles worth more than Tsar’s own mint.

For nearly two decades in the 19th century, roubles made from (nearly) pure platinum were standard currency in Russia, the first coins ever to be made from this metal. They were withdrawn in 1846, when the availability of cheaper platinum from Colombia made the roubles an attractive target for counterfeiters.1 Experts at the precious metals specialist firms Heraeus in Germany and Johnson Matthey in the UK, have now unleashed the whole arsenal of non-destructive analytical methods available today on a handful of surviving coins to establish how they were made and also how the real ones can be distinguished from the fakes.

Heraeus owns a set of four coins as well as a medal commemorating the coronation of Tsar Nicolas I in 1826. Density measurements on these coins confirmed that the platinum used in their manufacture was less than pure.2 The main contaminants include Au, Ir, Rh, and Fe. Depending on the ratio of Fe over Ir, such coins are often ferromagnetic. The German researchers scrutinised the surface structures of the coins using both optical and scanning microscopies, and analysed the interior using SQUID (superconducting quantum interference device) microscopy. Using these methods, the researchers established that the loose Pt ’sponge’ obtained from the dissolved phase must have been compacted by forging and rolling out before the coins were minted.

Johnson Matthey also holds four Pt rouble coins, whose provenance is subject to legend, but cannot be firmly established.

Detailed investigation by magnetic permeameter and density measurements, as well as by scanning electron microscopy and by x-ray diffraction revealed that two of these coins had a significantly higher purity than all authentic roubles known, and were likely counterfeited. This would have been a rash move for a modern-day counterfeiter: the historic three-rouble coins contain about 10 g Pt, which would now be worth about ?150, almost 8000 Russian roubles at the present exchange rate.

The two remaining coins, however, an 1830 six-rouble coin and an 1835 three-rouble coin matched all the characteristic properties for the Tsar’s platinum mint and were thus deemed authentic.3

Michael Gross