The South African Mint on Friday launched a sterling-silver R2 Crown and 2½c Tickey as part of its South African Inventions collectable coin series.

The coins featured a series of dolosse – concrete blocks in complex geometric shapes weighing up to 20 t that are used to protect harbour walls from the erosive force of the ocean during storms.

“The two coins come with a remarkable history and heritage. Under the new theme of South African Inventions, the R2 Crown and 2½c Tickey will offer coin collectors a lifetime of appreciation,” said South African Mint product developer Richard Stone.

Speaking to Engineering News Online, he explained that the reverse side of the R2 Crown depicted people standing on a harbour wall, protected by a number of dolosse.

It also showed a single dolos with the denomination ‘2½c’.

“Its obverse side features South Africa’s coat of arms, the year 2016 and the words ‘South Africa’ in all nine South African official languages, as well as a protea,” he said.

He added that the set, which was packaged with a miniature sterling silver mould in the shape of a dolos, was a source of pride where South African innovation was concerned, as the dolos “put South Africa on the map when it comes to harbour protection across the globe.”

“The dolos was developed by East London harbour engineer Eric Mowbray Merrifield and draughtsman Aubrey Kruger, whose images are both included on the coin,” he said.

Stone pointed out that the coin was the first to be manufactured by the South African Mint to contain shadows.

“We used the latest laser technology to achieve this; it helps create subtle nuancing that has never been done [by the South African Mint] before,” he said, adding that the process of including shadows on the coin was extremely labour intensive.

He pointed out that the coins took six months to manufacture and that they contained an enormous amount of engineering pride, showcased by the South African Mint for the first time.

“The coin is a great investment in craftsmanship and artistic integrity that will only appreciate in value,” he stated.

He further noted that the South African Mint would, in 2017, commemorate the fiftieth anniversary of the first heart transplant, performed by South African Christiaan Barnard, adding that there was a list of ten South African inventions that the manufacturer hoped to put on coins in the future.