It has passed from master potter to master potter. Bernard Leach, the father of British studio pottery, shipped it from Japan to London in 1943, where it had a brief but precarious existence during redecoration in the home of a friend in Hammersmith.
Leach wrote to his co-worker of future renown, Lucie Rie, begging her to rescue it. It remained in her studio for over 50 years, until Dame Lucie's death in 1995. She willed it to Leach's widow, Janet, who, bedridden in St Ives prior to her death last year, kept it at the foot of her bed and often gazed at it.
The entire Janet Leach collection is on offer in the sale - 544 lots of Japanese pots, paintings and textiles, plus signed and annotated first editions of her husband's books on the secrets of Japanese pottery.
There are 34 lots of ceramics by Shoji Hamada, who helped Bernard Leach set up his pottery in St Ives in 1920. They range from a big, 14in tall bulbous vase estimated at pounds 6,000-pounds 9,000 to a little black tea bowl estimated at pounds 60-pounds 90.
An exhibition of the work of Hamada (1894-1977), one of Japan's "living national treasures" is at Bonhams, coinciding with the sale.
Bonhams' auction of the Janet Leach Collection is its most significant since the sale of Dame Lucie's collection last year, which raised pounds 600,000. It is unrepeatable: Janet Leach was one of the last living founders of British studio pottery.
The tradition is being carried forward by a small group of collector- investors and by the young potters whose work they buy and promote. At their centre is Cyril Frankel, the film director and contemporary ceramics collector.
Then there is Sir Robert and Lady Sainsbury, founders of the Sainsbury Centre for Visual Arts at the University of East Anglia, and avid collectors Sir David Attenborough and Lord Queensberry.
Frankel's forthcoming book on the Sainsbury collection, "Lisa Sainsbury's Collection of Contemporary Ceramics" will be a Who's Who of successful potters.
His is an unusual operation. Young artists are traditionally promoted by galleries rather than by auctioneers, who lack the time and money to nurture them.
A gallery that signs up potters, was launched in London this year by Tatjana Marsden, a former director of CAA. But the number of specialist contemporary ceramics galleries in this country are still few.
Whereas in Japan, pottery is considered a higher artform than painting, in this country even the Tate Gallery disdains it. However, both Japanese and American collectors have taken to buying at auction here. Prices are still low compared with the paintings market, though a Rie masterwork that cost pounds 6,000 10 years ago would probably sell for double that price nowadays.
Here are four potters adopted by Frankel whose work has found favour with the friends of Lucie Rie and whose prices are rising. Work by all except Nagi is in the Sainsbury Collection.
1. Gabriele Koch. German, aged 49. Rie met her at an exhibition of her work at the Gillian Jason gallery in London 10 years ago, and recommended her to Frankel. In the first of Frankel's Bonhams sales 10 years ago, a 16in wide vessel of hers fetched pounds 374. Last year, a smaller one fetched pounds 690.
2. Christine Jones, 42. Rie told Frankel: "Look at this girl's beautiful forms." The prices she got in the same inaugural sale, 10 years ago, were double what she had expected; a 15in diameter bowl made pounds 286. This year, a tapering 22in high blue vase with characteristic pitted surface made pounds 690.
3. Abdo Nagi, 57. A former Yemeni goat-herd brought to this country as a domestic servant. Now resident in Letchworth, Hertfordshire, Nagi's lush glazes are unmistakably middle-Eastern. A delicately thrown bowl, 13in wide, sold, for pounds 132 10 years ago. This year, a 16in tall gently- tapering porcelain vase with narrow neck and blue glazing, made pounds 748. Prices are generally around pounds 300.
4. Rupert Spira, 38. Championed, while still unknown, by Frankel. Throws large stone-ware bowls, jars and plates in bold colours. Price range: pounds 100-pounds 500.
The Janet Leach Collection, Wednesday 16 September (11am). Shoji Hamada, Master Potter, exhibition until 17 September. Bonhams, Montpelier Street, London SW7 (0171-393 3900).