The betrothal had long since passed. Families had approved, wedding arrangements had been discussed, but still there was no ring. An initial cash-flow problem was exacerbated by the wait: the more time went by, the larger the eventual prize would have to be. And how to avoid a Ratneresque nightmare of substandard, worthless junk?

The solution: the delay would be more than forgotten or forgiven if a weekend in a foreign city was involved; and the diamond dealers of Antwerp would surely throw Gerald Ratner and his like into the river Schelde for daring to debase their profession.

Anyone arriving by car in Belgium's second city is strongly advised to buy a proper map, especially if the intention is to reach a particular street; otherwise some less than romantic exchanges will ensue - brought on by Antwerp's labyrinthine one-way systems, a tourist map that only bothers to name every third or fourth street, trams hurtling this way and that, and cobbles that give this already lethal cocktail a good shake.

But even after this unpromising start, it would be difficult to agree with Napoleon's description of the place as, "little better than a heap of ruins". The facades of Antwerp are majestic and intricate: a short walk along Mier, one of the busiest shopping streets, reveals some familiar corporate logos - M&S and C&A among them - but look up above the level of the glass display windows and you will see that your favourite multinational has bought into some splendid rococo masonry and ironwork.

This is not, though, a city of unrelenting beauty: many of the facades are badly in need of a good clean, and, like most port cities, it has its seedy side. The diamond district rather confirms the impression of Antwerp as a place too busy making money to worry about its appearance. The area around the neo-gothic Central Station is the scruffy hub of the world's diamond trade. Here, dozens of tiny shops - many of them run by descendants of the Jews who fled Eastern Europe in the last century - vie for your custom.

Here we met Yossi. A tubby man in his fifties, he almost filled the space behind the counter that runs the length of his narrow shop. At the far end, his son sat at a workbench making jewellery. As soon as they realised that we were serious customers, seating was provided, and a bottle of Coca-Cola was produced. With endless patience, he showed us his impressive collection until we felt sure we had found the ring. The solitaire seemed to dance in its setting as it caught and refracted the light.

"So, this is the one you like? You sure?"

We were sure. We couldn't wait to hand over a large bundle of Belgian francs and take it away.

"Right!" he said. "Now I am going to my safe to get some diamonds, and my son will take out these fakes and fix it up for you."

Well of course we'd known all along they weren't real.

Half an hour later we had our ring, adjusted for size, and complete with a certificate of authenticity. But our dealings with Yossi weren't yet over: to our horror, we found one of the small stones had worked loose and had vanished down the plughole after a spot of vigorous hand-washing. The phone was answered by Yossi himself at 8pm on a Saturday evening, and we were told to return the next day, when a new stone would be fitted, free of charge.

"Anything you buy from me is guaranteed for life," he said. "If you are happy, I am happy."

After an evening drinking fine Belgian beers, and eating at a a small restaurant in the old town, looking down on the other diners from our vantage point on a rickety wooden mezzanine, tasting local variants of old French favourites like soupe l'oignon and bouillabaisse, it would have been difficult not to have been, at the very least, content.