FOUR MONTHS AGO, Hong Kong-based violin restorer Sandra Wagstaff made one of the scariest decisions of her life. She had just a few hours to decide whether or not to buy her first ever Stradivarius violin and, because of a sudden acceleration in deadline when the owner decided he wanted to sell in the 2000 tax year, she didn't have all the investors she hoped for on board. Wagstaff had sold Strads before, but always on commission, as an agent for other people. This was the first time she and her husband Mike had decided to risk their own money. And it was a sizeable risk. The violin is now for sale for US$2.2 million (HK$17 million). All this went on an instrument that, in the comparatively dim light of a Zurich hotel room, had seemed fine enough, but which, unusually for a Stradivarius violin, was virtually unknown. 'We couldn't really afford to buy it - but we couldn't resist it,' Wagstaff says. No one knows how many instruments were made by Antonio Stradivari during his long lifetime. Probably 1,000, but many must have been destroyed in the late 18th century when northern Italy was part of the Austrian empire, few people played violins and the instruments were left uncared for until a dealer 50 years later started buying them wholesale and exporting them by the cartload to Paris. About 450 Stradivarius violins remain, as well as seven violas, 20 cellos, a couple of harps and even a guitar or two. They are in the hands of collectors, dealers, and also, most famously, pass between celebrated performers. Because of their age, their unrivalled quality, and their price - which, since the mid-19th century, has been equivalent to a mansion or at least a very fine town house - Stradivarius violins (the name of their maker traditionally Latinised in English) have been mythologised. People dream of finding a 'lost' Strad-ivarius in their attic. When a performer loses a Strad (as Pierre Amoyal did, to Italian gangsters, about five years ago, or as Bronislaw Huberman did in 1936 from his dressing room in Carnegie Hall) it makes international headlines. The Wagstaffs' violin has not exactly been lost, but it hasn't been found very much either. 'Everyone knew about it, but the owner wouldn't let it out of Switzerland. So it hadn't been endorsed by Charles Beare, because he hadn't seen it,' Wagstaff explained. Beare, based in London, is the world's foremost authority on violins. His endorsement is often seen as vital in the international violin market. He has now seen the violin. 'He said, 'I'm in love with it',' says Wagstaff, who trained under Beare in London many years ago. Unlike most high-quality Strads, this one has not been photographed a lot, and its history little published or researched. But the Wagstaffs have been busy over their books, discovering a rich provenance that is - as with the stories of other top violins - as much about the history of Europe as the history of music-making. Their Strad was made in 1687, when Stradivari was in his 40s, with 30 years or more of experience behind him. It appears to have remained with the family in Cremona, northern Italy, for nearly a century, because it next appears in 1772 with six other instruments sold by Stradivari's younger son Paolo to a Spanish priest, on behalf of King Carlos III of Spain. There it would have been played by professional musicians for the king's pleasure. It remained in Madrid for nearly 40 years: the king died and his son Carlos IV inherited the throne - and, of course, the Strad. But then Napoleon arrived on the European battlefield; he took Madrid and his soldiers took Spain's treasures. The violin, along with numerous works of art, found itself on an army cart, heading back to Paris as war loot. In 1850, it was bought by Maitre Dreux, a lawyer and enthusiastic amateur violinist. He must have been a successful lawyer, as 25 years later he could afford to give the valuable instrument to his teach-er Monsieur Lebrun, who was principal violinist in the Societe des Concerts, the leading orchestra in Paris. This is a Strad with no name. Or almost no name. Its previous owner, a Swiss businessman, dubbed it the 'Count Mersen' after the Swedish aristocrat who bought it in 1903. But that name, given for this sale, hasn't caught on with its new owners. The instrument's most famous owner was renowned Czech soloist Josef Suk and they have already contacted him to see whether it would be appropriate to name the instrument after him. 'He had it for nine years, then sold it in 1979 for a Golden Period Strad,' said Wagstaff. But he didn't like that one as much, so he sold it and bought another one which he has had for 20 years. 'It might be right for that violin to have his name . . . but perhaps it already has a name, I don't yet know.' It was not greatly photographed and for the past 21 years spent most of its time in a Swiss Bank at St Gallen, in the vault of architect Bruno Kopp. 'After we bought it, we went to pick it up from the bank,' says Wagstaff. Her description sounds like a scene from a bank heist movie: the formal meeting in the Swiss bank and the offer to take them down to the vaults. 'The door was a metre thick,' she says. After all that time in a vault, the violin needed some tender loving care - and Wagstaff needed to open it up to see whether it was as structurally sound as she had hoped. Opening up a multimillion- dollar instrument is almost as scary as buying one. 'You have to first separate the areas where there are blocks,' she says. 'You have to put in a thin blunt knife and ease it around to separate it, breaking the glue. You hear, 'Click, click, click', and if it goes quiet, you stop. Immediately,' she smiled. 'Because that means you're cutting into the wood.' Looking into the interior of the violin she says she was thrilled to find it had hardly been touched by the restorer's combination of gauges and glue. There was only one patch - most Strads have more - that was put on in the 19th century, which meant it had escaped the excessive patching trend of the 20th. 'Performers usually prefer violins that haven't been patched a lot: it often affects the sound and they can also be much more temperamental to changes in climate. And if you're an international soloist playing 200 concerts a year all around the world you need to trust that it won't play up.' This is now the first Strad to be owned by anyone living in China. The Wagstaffs have several potential buyers interested in the instrument. They cannot give details but at least two are world-class Europe-based soloists. And one possible buyer, they reveal, is on the mainland. 'In one way we would love it to be bought by a famous soloist. But in another way, we hope that the Chinese sale comes through. It would be wonderful to have a Strad being played in China.'