International laws such as Unidrois convention that deal with cases of disputed cultural property (Through their adoption by UNESCO) are seen by many as a good thing – although clearly not by all, as many countries have yet to subscribe to these conventions. The conventions do not act retrospectively however – so there is a strong argument that they have created a division in the market – between those artefacts acquired before the convention came into force & those acquired afterwards. Many collectors fear that these conventions are devaluing their collections – but this point is counterbalanced byt the fact that is the artefact was acquired legitimately & has good provenance (which is the only real way of proving that it was acquired legitimately) then there should not be any problems.
New York Times 
Wanted: Antiquities Beyond Reproach
By SOUREN MELIKIAN
Published: December 17, 2010
NEW YORK — The impact of the Unidroit convention, adopted by Unesco when endeavoring to protect the artistic heritage of mankind, starting with its archaeological treasures, is beginning to make itself as never before, although not quite in the way that its promoters expected.
By all accounts, the terrifying destruction of archaeological sites goes on, from Syria to Afghanistan to Nepal. But on the auction scene the consequence of Unidroit, to which only a few countries subscribe, is that some collectors live in fear that their favorite game, buying the relics of antiquity, may soon end. Many suspect that objects that cannot be proved to have been acquired before 1970 — the cutoff date set by the Unidroit convention — will become financially worthless or exceedingly difficult to negotiate.
Add to this new frame of mind the rapidly developing passion for works that have a documented place in the history of art and culture, particularly those spelling out the names of historical characters.
The effect at auction is phenomenal. Its full measure could be taken at the Sotheby’s Dec. 7 sale devoted to 38 works of art that had belonged to the collector Clarence Day, who died last year in his hometown of Memphis, Tennessee.
The gentleman had assembled his objects over some 30 years. You can tell if a collection was truly built by a connoisseur motivated by the pursuit of beauty, not the desire to impress nor to invest, when it includes some seemingly simple objects perfect in shape as in color, or rarities of supreme sophistication that do not immediately advertise themselves as such.
Both categories were represented among Mr. Day’s possessions. A small two-handled bowl of the skyphos type from fifth century B.C. Greece matched the first category in its spartan quality — even if it was a typical black-glazed Attic piece. Opening the session, it sold for triple the high estimate, $43,750.
It was followed by unobtrusive rarities that fell into the second category. A Greek bronze horse in the so-called Geometric style, probably cast in the eighth century B.C., was expected by Sotheby’s to bring $150,000 to $200,000 plus the 25 percent sale charge. It ended up at $842,500. The bronze is a supreme example of an object that is likely to be unobtainable in the future, both because collections such as Mr. Day’s are increasingly rare — the knowledge, the patience, the dedication are gone — and because when pieces of this caliber, previously unrecorded, turn up, questions are asked about the legitimacy of their acquisition.
Similar thoughts may account for the astonishing $662,500 that greeted the bronze figure of a warrior cast around 530-520 B.C. just after the Geometric horse’s appearance.
It is only in such a context that the price paid for a damaged marble bust of a young man identified on the pedestal in Greek capitals as Antinous, the Roman emperor Hadrian’s favorite who died in 130 A.D., can be understood. Sotheby’s experts Florent Heintz and Dick Keresey gave it a $2 million to $3 million estimate. The bust made $23.82 million.
Looking at the damaged piece, the best professionals could not have foreseen this astronomical price. The historical significance of the bust partly explains it. It is the only three-dimensional portrait of Antinous identified as such by an inscription on the piece. Better, the man who commissioned it was the scion of an ancient patrician family from Rome, Lucius Flaccus, whose name is given in Greek form, Lukkios Flakkos.
But the documented history of the sculpture in modern times made it impeccably kosher in Unesco terms. It came to light in the Syrian town of Banias on the Golan Heights and was acquired not later than 1879 by the Chancellor of the French consulate in Beirut, as is established in the journal where its important Greek inscription was published in 1879. In recent years, nothing approaching the attention the bust received in December could be observed as it passed through the hands of famous dealers — Nicolas Koutoulakis of Geneva and Paris, Robin Symes of London, Albrecht Neuhaus of Würzburg and Jean-Luc Chalmin of Paris all handled it — before Mr. Day bought it in 1992. The damage probably turned off many, as did a price that, if set around Sotheby’s “low estimate,” must have been deemed enormous.
The story repeats itself with variations in the case of Mr. Day’s green porphyry sphinx carved in Rome in the Egyptian style possibly at the end of the first century A.D. Looked at from a distance, with its decidedly spoofy touch, the human-headed feline creature could be mistaken for an 18th- or 19th-century poor imitation of the Ancient Egyptian style.
Scholars say it is a Roman attempt at imitating an Egyptian black granite sphinx dating from the reign of Tuthmosis III. The Roman piece is, however, larger and more angular than the Egyptian original. The assumption is that it was recovered in the 19th century, although where and when cannot be ascertained, nor is it clear why it was only published as late as 1972.
However, it is in the sphinxes’ nature to be enigmatic, and 1972 is close enough to 1970. The prospect that it might have come from a temple celebrating the mystery of Isis under the rule of Domitian (81-96 A.D.), who restored the Iseum, added to its tickle. The silent laugh of the human-headed lioness suggests that it was amused at the $5.23 million bill that this month’s buyer had to settle — four times what Sotheby’s thought it might cost.
Two lots down another object, this time truly Egyptian, verified the new luster acquired by Egyptian historic sculpture with a documented record meeting the Unesco criteria. The limestone statuette of the ushabti type once belonged to an overseer of the cattle in the temple of Amun between 1292 and 1190 B.C. This is no earth-shaking masterpiece. But, Sotheby’s noted, it “is one of a very small group of private ushaptis (all for different owners) with the hallowed Khamuas formula” — a magical spell coined by Khamuas, a son of Ramesses II. Not least, the statuette with the magical spell was published in 1929 as part of the collection of the “late Omar Pasha Sultan.” And magic it must have been that raised the price from a piddling $200,000 to $300,000 estimate to $1.31 million.
The most striking evidence of the fetishist approach to antiquities enhanced by a whiff of history, even though robbed by their distressed condition of artistic appeal, came a day later at Sotheby’s second sale of antiquities. It was provided by a badly mutilated marble group that had been removed from a monument still in Rome.
The satyr riding a sea-goat is one of four identical groups that surrounded a basin. The other three still attached to the fluted stand of the now-vanished basin lack heads, and the sea-goats they ride are reduced to formless fragments. By contrast, the satyr and the sea-goat in the Sotheby’s group are preserved in the main. Florent Heintz’s stroke of genius was to trace back the fragment to the Rome monument from two old photographs and to show that it had left Rome for Munich by 1908.
While handled by a Paris dealer after World War II, it attracted little attention. On June 23, 2009, the group turned up at an Artcurial auction, where it brought what seemed at the time a strong price, €124,500 or about $170,000. Not to the professional with a better sense of what is in the wind than most, who settled the bill and consigned it to Sotheby’s Dec. 8 sale hoping it would be knocked down between $250,000 and $350,000. It brought $1.98 million with the sale charge.
At Christie’s, on Dec. 9, the certainty of buying within the rules defined by Unidroit alone was sufficient to trigger a stupendous bidding match over a Cycladic standing character more clearly figural than the earlier very abstract-looking marbles. It was included in the Zurich 1965 show “The Legacy of Antiquity: Masterpieces from Swiss Collections” and that made it blameless. “The Schuster Master,” as Christie’s put it, carried a $3 million to $5 million estimate. At $16.88 million with the sale charge, it tripled expectations.