The rarest Proof set in South African coinage history is the one issued in 1892.

An example of the set highlights Stephan Welz & Co.’s May 14 and 15 auction in Johannesburg.

The set, when complete, has nine coins: penny, threepence, sixpence, shilling, 2-shilling piece, 2.5-shilling piece, 5-shilling piece, half pond and pond. The latter two coins were struck in gold. The penny is composed of bronze, and the remaining coins are composed of silver.

Ten complete 1892 Proof sets are known, the auction firm reports, based on research by Brian Hern in Hern’s Handbook on South African Coins and Patterns.

The coins show Paul Kruger, state president of the South African Republic, on the obverse, with most of the coins depicting the coat of arms on the reverse.

Though a mint was being built at Pretoria, Kruger, in the midst a re-election campaign and seeking to boost his profile, contracted with the Berlin Mint to design and produce the South African currency bearing his image, with mintages for many denominations in the thousands. 

But in his use of a European mint, Kruger almost jeopardized his fortunes instead.

German designer Otto Schultz created one of the most spectacular unintentional design errors, using a European style wagon on the coat of arms instead of the style typical in South Africa. The wagon on the coins had two shafts, not the single-shaft version that was commonly hitched to a pair of oxen.

The rear wheels on the native Voortrekker wagons also have rear wheels that are larger than the front wheels, but Schultz’s design has wheels of equal size. Schultz’s OS initials (below Kruger’s bust) were also mistaken for the Afrikaaner word for "ox."

The improperly designed coins had to be withdrawn from circulation, and examples with a single shaft wagon were issued in their place.

People kept enough examples of the wrong design that the coins are relatively available today.

However, only a small number of Proof versions were struck, with the 5-shilling coin and half pond struck only with the double-shaft designs. The set in this auction has a pond coin also bearing the double-shaft design, while the remaining six denominations in the set bear the single-shaft design.

The set in the auction is from the Erich Albrecht Hohmann Collection, and all nine coins are “Brilliant Proof,” according to the firm. 

The set has an estimate of 1.6 million rand to 2.5 million rand (about $151,653 to $236,968 in U.S. funds).

The auction will take place at Stephan Welz & Co’s new premises in Mandela Square, Sandton City. More than 1,100 items are in the sale.

A full catalog may be viewed at the firm’s website, ww.stephanwelzandco.co.za, and live bidding is available on www.the-saleroom.com.

For more information about the auction, telephone the firm at (011) 27 11 880 3125 or visit the website.