It is one of the finest surviving examples of the work of 17th-century Spanish goldsmiths, and Christie's expects it to cause a sensation when it is auctioned in New York in November on behalf of an American owner who is keeping his or her identity secret. It will be exhibited all round the world beforehand - in Madrid, Hong Kong, Tokyo, Mexico City and other locations. There will be a London showing in September.
The crown was made for a more than life-size statue of the Virgin which belonged to the cathedral of Popayan in Colombia, a city founded by the conquistadors in the 16th century. It was a frontier town during the Spanish gold rush and became a bishopric in 1547; the Jesuits founded a university and built a cathedral there in the prosperous years that followed. With many beautiful old buildings, it is often referred to as the "Florence" of South America.
According to legend, the crown was a thanks offering for deliverance from the plague. A devastating epidemic of smallpox swept the nearby coastal regions around 1590, and the terrified population of Popayan prayed to the Virgin for help. Miraculously, the epidemic avoided the city, and in gratitude a group of local noblemen is said to have commissioned the crown. They stipulated that it "must exceed in beauty, in grandeur and in value the crown of any reigning monarch on earth, else it would not be a becoming gift to the Queen of Heaven". The Coronation of the Virgin in the cathedral took place in 1599, an elaborate ceremony.
That, at least, is how local historians describe it. Christopher Hartop, the expert at Christie's, suggests the bottom half of the crown - a circlet rising to eight points, pierced and embossed with elaborately entwined acanthus scrolls and applied with clusters of table-cut emeralds - dates from the 17th century. The two intersecting arches, also pierced and set with emeralds, date from the 18th century, along with the orb surmounting them - while the little cross supported by the orb, the earliest part of the confection, probably dates from the 16th century.
Hartop thinks the crown evolved over time. It could have started off in 1599 as a solid band of gold, which was subsequently pierced and decorated to match a new superstructure. The little clusters of emeralds resemble the dress mounts of the period; in the 17th century, aristocratic dress was embroidered with jewels. It looks as if the faithful contributed locally- made dress mounts to embellish the Virgin's crown, and it grew steadily richer as the years went by.
Both gold and emeralds were local products. It was their quest for "El Dorado", a mythical golden city, that carried the Spanish conquerors to South America; when Francisco Pisarro captured the Inca ruler Atahualpa in 1532, he is said to have been riding in a litter made from 190lb of gold, paved with clusters of emeralds. The largest emerald in the crown, weighing 45 carats, is known as the Atahualpa Emerald and is reputed to have been among the stones seized from the king by the Spanish.
It took the Spaniards many years to find the emerald mines at Muzo and Chivor in the jungles of Colombia, where the stones in the crown were quarried. Colombian emeralds have been considered the finest in the world ever since - the best of them were acquired by the Mogul rulers of India. The crown represents an exceptional collection in terms of quantity, though the quality of the stones is variable.
The crown, together with the other ecclesiastical treasures of Popayan, was seen only once a year during the spectacular processions organised to celebrate Holy Week - which still take place today. To protect them, the local noblemen organised a group called the Confraternity of the Immaculate Conception. They divided the treasures between them and hid them separately; the crown is said to have been dismantled and divided between several guardians. That is how it survived into the 20th century, when most other jewellery of the period was melted down and the stones prised from their old settings and remounted.
Indeed, it is almost miraculous that the crown avoided this fate. In the early years of the 20th century the cathedral decided to sell it and use the proceeds to build an orphanage, a hospital and a home for the aged. In 1914 Pope Pius X granted permission for the sale, but it wasn't until 1936 that the Confraternity of the Immaculate Conception found a buyer, a syndicate of American gem dealers.
Its leader, Warren J Piper of Chicago, had first heard of the crown in 1915; it took him 20 years to find the necessary partners and negotiate the purchase. The syndicate put it on show at the Waldorf-Astoria in New York in June 1936 and, according to the New York Times, "Mr Piper was at hand, pistol on hip, to answer questions". He told the press that the syndicate intended to dismantle the crown and sell the emeralds piecemeal as a "money investment".
Piper did not reveal the price the syndicate had paid, but he stated that emeralds sold for $3,000 a carat and that the crown contained 1,500 carats of them. "When it was pointed out to him that this would make the crown worth $4,500,000, he made no objection to the estimate," according to the New York Times. As a result, the crown was exhibited all over America under placards announcing that it was "valued at millions of dollars" - it was not, in fact, worth anything like a million in the 1930s.
The syndicate discovered that exhibiting the crown at industrial shows was a lucrative sideline, and never got round to dismantling it. In November 1937 it was borrowed by General Motors for the inauguration of its new Chevrolets in Detroit; it attracted 225,000 visitors in a week, 15 per cent of the population of the city. It was shown at the New York World's Fair in 1939, and popped up again at the Royal Ontario Museum in 1959 - but by then the syndicate was losing heart. In 1963 it was consigned to Sotheby's in London for sale, but the bidding reached only pounds 55,000; the price was not high enough and the syndicate got one of its colleagues, Asscher of Amsterdam, to buy it back for them. Since then it has lived in a bank vault.
Christie's has not revealed the identity of the present owner beyond saying it belongs to a descendant of one of the original syndicate. My researches suggest it belongs to Alice Heyman, a descendant of Oscar Heyman of New York, a well-known jewellery manufacturer. Now in her fifties, she was a founder of the First Woman's Bank established in New York in the 1960s.
The existence of the crown was not forgotten while it sat in its bank vault, however. In 1982 the American jewel historian Neil Letson researched its romantic history and published his findings in Connoisseur magazine. By a strange coincidence, a devastating earthquake struck Popayan the following year. About 85 per cent of the the city was damaged and at least 250 people were killed; the domes of the cathedral collapsed, crushing worshippers.
In the aftermath of the earthquake, it emerged that the city's superb ecclesiastical treasures had survived because they had been hidden by the old Confraternity. Letson was permitted to publish the first scholarly account of them. He was shown the polychrome statue of the Virgin, for whom the crown was made, languishing in a dusty outhouse; separately, he was shown the emerald earrings and necklace which she had worn to match the crown.
The treasures of Popayan, Neil Letson tells me, were still closely guarded by the Confraternity of the Immaculate Conception. On one occasion he and his photographer were taken at the dead of night to a school building. "Out of the night came men with boxes," he recalls. "They took out parts of a magnificent monstrance, put them together and gave us 45 minutes to photograph the piece. Then they departed into the night. They were guarding it secretly, just as they would have done the crown in earlier times." !