Brilliantly coloured enamels - made from glass which has melted and fused to a metal surface - were considered as rare and desirable as jewels by the craftsmen of the Middle Ages. Shrines, caskets and crucifixes, as well as luxury household goods, sparkled with colour, partly on account of their embellishment with precious and semi-precious stones and partly on account of these bright enamel plaques.
Today no costume romance is complete without them. Bright primary colours have become the signature tune of the Middle Ages. But when do you actually see medieval enamels? Almost never. The days when you could turn up a piece in a junk shop - if you could recognise it - are long gone. And it is 20 years since the last important collection was seen at auction.
This week's exhibition of the Keir collection at Sotheby's in Bond Street is a major event. Valued at around pounds 20m, it is the finest collection of medieval enamels left in private hands. And Bond Street is only one stop on the world tour Sotheby's has organised for the collection, which will be auctioned in New York in November.
Some of the pieces are very small. Plaques may only be an inch or so across and should be regarded, as they were in the Middle Ages, as jewelled pictures. Sotheby's has wonderful little plaques with abstract patterning, about 3 by 112in, which must once have embellished a casket or shrine and which are now priced around pounds 3,000 to pounds 4,000. Other plaques have undulating patterns of foliage and others again are essentially copper pictures from the Bible story coloured in with enamels. The more sophisticated the picture, the higher the price. The two most mag- nificent plaques, one depicting angels with multi-coloured wings and the other royal martyrs, are expected to reach around pounds 2m each - though each measures little more than 6in across.
Although the technique of enamelling was known in antiquity, there was a great flowering of the art in the Middle Ages. The fashion began at the court of the Byzantine emperor in Constantinople in the 10th century. Two hundred or so years later, the main centre of production had shifted to France. From the 12th to the 14th century, the workshops of Limoges supplied their marvellous creations to clients all over Europe, while other craftsmen were at work in Spain, Germany, Italy and the Low Countries - the "Mosan" enamels made in the region of the river Meuse rival the fame of Limoges.
The usual practice at this time was to apply the enamels to copper. Coloured glass was ground to powder, then either used to fill a pattern made with raised wires on top of a copper plate - this is called cloisonne enamelling - or to fill troughs gouged out of the metal - which is called champleve. When raised to a high temperature, the powdered glass melts and fuses to the metal. In the 15th century, a technique was found for literally painting a copper plate with ground glass, which was then melted to form a highly finished picture. All of these techniques are represented in the Keir collection.
One can't help feeling sorry that it has to be broken up and dispersed. But apparently no museum, not even in the United States, was ready to put a hand in its pocket and come up with the pounds 20m needed to purchase the collection en bloc. And money matters in this case, since the collection belongs to a group of friends who bought it as an investment back in the early Seventies. The "in-vestment" has since matured through loans to museums. The British Museum mounted an exhibition of the star items in 1981, and from 1982 to 1996 the whole collection was on loan to the Nelson- Atkins Museum in Kansas City. Now the time has come to realise the profits of a very clever placement of money.
The mastermind behind the collection is Edmund de Unger, now in his seventies, and best known as a great collector of Islamic art - the scholarly catalogue of his collection runs to five volumes. He is Hungarian by birth, but settled in Britain in the late-Forties to escape the Communist regime, and became a barrister. His career flourished and he is now a tax exile, resident in Switzerland - though he still keeps his art collection in Britain. Rather than puff up his own name, he christened it "the Keir collection" after Keir House in Wimbledon where he used to live.
"In the early Seventies, the idea of art investment was very fashionable," Unger explains. "It was the time when Sotheby's was buying for the British Rail Pension Fund. A group of friends in Switzerland asked me if I would buy for them and I thought it would be fun. I don't get paid for doing it but from time to time they give me a present - a work of art." He recently decided that it was time for him to "retire" from the job. He told his friends they must find a new curator or sell up - and the result is the Sotheby's auction.
He put his investors on to medieval enamels when a unique opportunity arose. Ernst and Martha Kofler-Truniger were selling their collection - which is where all but 20 or so of the Keir enamels came from. "Ernst had a department store in Lucerne," Unger explains, "but he was not much interested in it. He went to Egypt every year from 1948 onwards. He had a wonderful Pharaonic collection and a very good Islamic collection. He looked for collection fields where there was a possibility of growth." The Kofler collection is now dispersed around the world. His ancient glass caused a sensation when it was auctioned at Christie's in 1985; and his 10 best medieval ivories ended up in the Metropolitan Museum in New York.
Unger bought Kofler's medieval enamels for his friends and he added to the collection. "He had a lot of Limoges enamels and I tried to add Mosan, also some statues and little pieces. But there is very little medieval material around. Good material, I mean."
The star lot in Sotheby's sale is a 12in copper statue of the Virgin and Child which comes from the Abbey of San Pedro de Arlanza, near Burgos in Spain. Made in Limoges around 1225-35 she is known as the Virgen de las Batallas since the Spaniards used to carry her into battle to ensure them victory. At the back of her throne a copper door opens into a space designed to hold the "host" - consecrated bread, miraculously transformed into Christ's body.
Her crown was once encrusted with jewels - which have been gouged out by some greedy hand - but her enamel eyes remain, as do the rich blue, green, red and yellow enamels which adorn the base of the statue. Sotheby's rank her importance as highly as the enamelled base of a candlestick which they sold last year for pounds 4.4m, a record price for medieval enamel. In the same sale, a reliquary casket applied with enamelled plaques depicting St Thomas a Becket was sold to Lord Thomson of Fleet for pounds 4.2m but there was such a furore about his taking this memorial of the most famous British martyr to his home in Canada that he withdrew in favour of the Victoria and Albert Museum - the Heritage Memorial Fund came up with the money.
The Keir sale includes a comparable reliquary made in Limoges in the 12th century decorated with Christ in Majesty and the Apostles. The coloured enamels are only applied to the drapery of the figures and the decorative borders, making a rich contrast with the gilded copper background. All the figures have three-dimensional copper heads, including the angel, eagle and two griffins who guard the figure of Christ. The background is engraved with scrolling foliage in a style known as vermicule, a "technical" term invented by a 19th-century collector who decided the pattern reminded him of worms - ver means worm in French.
The earliest piece in the sale is a battered Byzantine roundel, 112 inches in diameter, dating from the 9th century and depicting St Dimitrios, an early Christian martyr and patron saint of Thessaloniki in Greece (estimate pounds 15,000 to pounds 20,000).
There are many plaques which would originally have decorated such items as shrines, caskets and crucifixes, a crosier head and four "gemellions" - basins for washing guests' hands at the table. Gemellion derives from the Latin gemellus meaning twin because the basins were used in pairs - perfumed water was poured from one to the other, over the guests' hands. The decoration of these pieces movingly echoes the age of chivalry by combining armorials and scenes of courtly life. Estimates vary between pounds 50,000 and pounds 140,000.
While all these enamels are estimated at what could be considered jewellery prices, there is a very sharp divide between the astronomic figures expected for the very best and the estimates for the rest. This is a collecting field which has really become too rare to attract the interest of collectors - who need to be able to buy in some quantity. There are always takers for major items among museums and mega-rich collectors, but there is not much competition for the lesser pieces. Sotheby's has wisely decided to sell in the US where there's plenty of money swir-ling round the art market but, even so, some of its estimates may prove too high.
The Keir collection is on view at Sotheby's, 34-35 New Bond Street from 7-9 October. Auction at Sotheby's New York, 20 November
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