Cullinan, Diamond

Diamonds on the Soles of My Shoes: Cullinan Diamond Mine

Road sign by dusty road with a diamondWell, maybe not diamonds, maybe just diamond dust.  Even that is probably wishful thinking having listened to all the checks and balances in place to mine and refine every nanogram of diamond matter blasted out of the famous Cullinan Diamond mine situated just a little over an hour from Johannesburg.  Looking to inject some sparkle into my week, I had joined 15 other expat ladies for a surface tour of Cullinan.

Donning fetching blue helmets we explored the above ground workings, which looked remarkably like a giant Meccano set.  It was fascinating stuff.  Our guide had a wealth of knowledge about the history of Cullinan, the geology, and imparted mind boggling facts and figures about diamond mining.

The Town of Cullinan

The eponymous town that developed around the mine-works is quaint and Victorian.  The buildings are low-rise and mostly clapboard, with corrugated metal roofs.  A string of quirky cafes and jewelry shops flank one side of the street leading to Cullinans’ gates and on the opposite there is a pretty whitewashed church.  Instead of the soup or pasta of the day we were rather enticed by the ‘Today’s Specials’ board advertising diamond jewelry!

Specials Board in Cullinan advertising diamond jewellery

I hadn’t realised that diamonds form exclusively in volcano pipes, alluvial diamonds inclusive.  Cased in soluble Kimberlite (named after another famous diamond mine) diamonds can be washed down rivers and even out to sea, so if you happen to stumble across a sparkler on the beach you would need to follow the river to find the source which is exactly what Mr Thomas Cullinan did back in 1898.  Mining proper commenced in 1903 and in 1905 The Cullinan Diamond was discovered.

The Cullinan Diamond

The Cullinan Diamond is the most famous in the world, being the largest raw diamond ever discovered anywhere.  Presented to our very own King Edward it birthed 9 famous gems and approximately 96 smaller brilliant diamonds.  The mine is also the primary source of extremely rare blue diamonds.  Diamonds come in just about every colour.  In this case the inclusion of the rare element boron results in blue diamonds.

The Cullinan Mine

Cullinan is a working mine and produces approximately 4,500ct of diamonds daily. Roughly 80% will be industry grade and only 20% gems.  Gems can only be cut with other gems – otherwise the gem and industrial grade diamond dust produced will get mixed up.  Some 25% of the worlds gem supply comes from Cullinan.   It takes a whopping 11,000 tonnes of kimberlite each day to produce the couple of handfuls of daily output.

Diamond pipes are carrot (not of course to be confused with carat) shape, so the deeper the mine becomes, the narrower the circumference of the diamond field.  Petra Diamonds, Cullinans’ current owners bought it from De Beers in recent years.  De Beers had explored 800m below the current seem of glitter and not finding anything sold up.  Petra had taken a huge gamble but immediately bored down to 1000m and struck gold (well diamonds actually) at 850m.  There is still a lifetimes’ worth of diamonds to be mined.  Petras’ second coup was the decision to re-process the old mine dumps.  They are systematically trawling through 100 years of mountainous rock waste, which is proving very very lucrative.

Safety and Theft Prevention at Cullinan

The mine has a proud safety record.  One of the many measures in place is a strict weekly overtime limit of 10 hours to prevent overtired workers. However, when we visited, celebrations of a substantial and rare blue diamond find at the mine were bittersweet, coinciding with the first fatality in 7 years.

In terms of theft prevention, employees are subject to random searches and polygraphs.  Much of the work is done by machinery so there is virtually no handling of mined material.  In fact, even on the surface there are stringent rules (for workers and tourists alike) that nothing may be touched or picked up from the ground.

Should a miner spot a diamond sticking out of a lump of Kimberlite, they must go through the proper channels and alert security to their find.  Petra will record the find, and once the stone is extracted, pay a finders fee equal to the stones’ market value.  Just as we were forming an orderly queue to go and toil in the bowels of the earth (even the lady who had been aghast to hear that there were women employed by Cullinan had a brief maniacal gleam in her eye) our guide cautioned that such finds were slim to diamond dust rare.

The gift shop was a little more upmarket that your usual tourist tat, not a magnet, postcard or googly-eyed pencil in sight, (perhaps what Mr Incredible was envisaging when he asked whether I’d bought anything?).  Presided over by large black and white photographs of Elizabeth II and Elizabeth Taylor the only souvenirs for sale were glittering baubles displayed in locked glass cabinets.

The Cullinan Star

The Cullinan Star is a brilliant diamond (round 58 facets) with a star (an extra 8 facets) cut in the bottom of the stone bringing the facets to a blinding 66.  Only top quality stones mined at Cullinan may become ‘stars’ and we were able to admire one under a magnifying glass.

You can select a loose stone and the type of setting you desire and watch it being set on the spot, tropical juice in hand.  All of us being ‘residents’ rather than tourists, there was no smell of burning credit card plastic wafting back to our husbands in Johannesburg.  Just carefully pricing up of wish-list items followed by discussions and contact swapping on the way home.

How to Visit

I can highly recommend this gem of a tour, although having photographed the explosives wagon while surrounded by vats of ammonium something or other I noticed big signs all around with pictures of cell phones with big red crosses through them and then realised that the majority of our group were blithely waving their cell phones about getting snap happy.

Explosives wagon at Cullinan Diamond mine

Ours was a surface tour, but you can also explore underground.  If you are interested in a visit to Cullinan, it is best to arrange this in advance.  Here are a list of operators: 

January 2014

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