PARIS (REUTERS).- France’s Louvre museum is making an unprecedented appeal to the general public to help it raise the cash to buy a 16th century painting deemed a national treasure by art experts. The Louvre has already scraped together 3 million euros ($4.19 million) for “The Three Graces,” an oil painting of three nudes by German artist Lucas Cranach the Elder, but is a million euros short of the price tag set by the work’s private owners. The Louvre has until the end of January to raise the funds, without which it fears the masterpiece could go to another private collector and never go on public display, or worse, be taken out of France. Painted in 1531, the work is an ironic and provocative take on the Renaissance theme of the three graces, depicting the nudes in a mildly daring pose that the Louvre believes could make it a headlining piece of its collections. The central