March 23, 2013 -- As jewelry goes, it is modest, a simple diamond and sapphire ring. But it is rich in history.
The ring, which will be auctioned off in Paris on Sunday, was Napoleon's engagement ring in 1796 to the woman who would become Empress Josephine.
The gold ring has an 18th century setting called "toi et moi" with opposing tear shaped jewels, a blue sapphire and a diamond. The carat weight of the two gems is little less than a carat each.
This ring will go on sale at the Osenat auction house in Fontainebleau outside Paris where the bidding is expected to reach at least 15,000 euros, something close to $20,000. But the auction house said there will be more than two dozen international bidders on phones and online as well as those in the bidding room, which is expected to drive the price up higher.
The ring may seem unimpressive considering the names attached to them are an emperor and empress, but it actually illustrates Napoleon's passion for his future queen.
"At the time Napoleon was a young and promising officer, but he was not rich. He must have broken his wallet to buy this quality ring," Osenat's expert Jean-Christophe Chataignier told ABCNews.com.
The auction is also being held on a unique day.
"The auction will celebrate 250th anniversary of Josephine's birth," says historian David Chanteranne, the editor in chief of Napoleon I Magazine.
Napoleon met Josephine, (Rose Tascher de la Pagerie as she was known then) in September 1795. She was 32 years old, six years older than Bonaparte. At the time she was the rich and stylish widow of Alexandre de Beauharnais, an aristocrat who supported the French Revolution but died on the guillotine. Her first marriage produced two children, Eugene and Hortense, who Napoleon later adopted.
According to Napoleon's memoirs written at St. Helena, he met Josephine when her son Eugene came to ask him for the right to keep his father's sword. Napoleon said yes, and Josephine invited him to her apartment in Paris to thank him. Napoleon was immediately smitten, and within the first couple months of their relationship had fallen completely in love with her. He wrote about this in his memoirs:
"Everyone knows the extreme grace of the Empress Josephine and her sweet and attractive manners. The acquaintance soon became intimate and tender, and it was not long before we married."
The wedding day was March 9, 1796, but the honeymoon lasted only 36 hours. Napoleon left to lead the French army on a successful invasion of Italy, but during this absence he wrote frequently, sometimes twice a day.
"Since I left you, I have been constantly depressed," one letter says. "My happiness is to be near you. Incessantly I live over in my memory your caresses, your tears, your affectionate solicitude."
"How happy I would be if I could assist you at your undressing," the Emperor writes, "the little firm white breast, the adorable face, the hair tied up in a scarf a la creole."
Napoleon begged Josephine to join him in on his conquest in Milan, but Josephine was often unresponsive, preferring Paris where her kids attended school to the front line in Italy. And the there was her Parisian affair with Lt. Hippolyte Charles.
When Napoleon learned about Josephine's affairs, his letters changed in tone: "I don't love you, not at all; on the contrary I detest you – You're a naughty, gawky, foolish slut."
The marriage didn't last, but "Josephine continued to treasure the ring and gave it to her daughter Hortense, later Queen of Holland, through whom it came down to her son, Napoleon III and his wife Empress Eugene to whose family this relic ring still belongs," claims Chataignier.
The buyer will be breaking up something of a set. The ring is currently on display alongside other historic treasures, including portraits of Napoleon's son and a sword given to the emperor by King Henry IV.