The Cartier Pebble Watch and Jean-Jacques Cartier

Man in glasses and suit, beside a gold Cartier watch with square dial and brown strap.

Another week, another record for vintage Cartier London. This time the spotlight was on the Cartier Pebble (sometimes known as the 'baseball'), which was up for auction at Phillips in Geneva with an estimate of CHF 50,000–100,000.

This one was made in 1972, under my grandfather Jean-Jacques Cartier. An artist at heart, he was a lover of design (pictured here just after studying at the École des Arts Décoratifs).

As with all Cartier London watches at that time, the unusual gold pebble-shaped case was made in the Wright and Davies workshop in Clerkenwell by a skilled goldsmith — most likely the highly skilled workshop head, Sam Mayo.

Once checked, the cases would be packed into a briefcase with the other cases, deployment buckles and made-to-measure straps completed that week, and given to the young apprentice who would jump on the 38 bus to Piccadilly Circus and walk the ten minutes to 175 New Bond Street.

No taxis, security vans or security guards: the tried and tested Cartier formula was that no one would ever suspect a scruffy-looking boy on a bus was carrying anything worth stealing. Entering through the staff entrance, the apprentice would head upstairs into the small watchmaking division and hand everything over to master watchmaker Eric Denton.

What's amazing about these watches is that so many individual parts were handmade: from the case to the dial, to the hands, to the sapphire winder. Each watch took several months to make and if you wanted one, you put your name on the waiting list and just had to wait.

Today, you're likely to wait even longer for these vintage pebbles — they are even rarer than the more famous Crash Watch, and the few that Jean-Jacques did make were in two sizes for men and women.

Some auctions are almost gladiatorial — yesterday's was like that. The bidding was fast and furious, ultimately coming down to blow after blow between two bidders: one in Michigan and the other in Monaco. And the final price? I think even my grandfather would have been astounded: a mind-blowing CHF 403,200.