This ring is interesting. The division insignia is missing the "MOUNTAIN" tab and it is upside down! Obviously the designer was not very knowledgeable about the 10th Mountain Division.

The seller does not specifically state that it is of WWII vintage, but he did seem to focus on the WWII phase of the division's history in his description. It is unlikely that this dates to the WWII period. The division was disbanded so quickly after the war that very few souvenir items were made for the division. Once the division came home from Italy, most of the men were home on furlough or being discharged. Within two month of returning home, the division ceased to exist. That left little time or market for creating and selling items like this ring.

Most likely, this ring is a post-war item made for the veterans, in which case it probably date to the 1970s or later when the 10th Mountain Association really became active and began producing divisional memorabilia. It could have also been made for the "new" 10th Mountain Division that was reactivated in 1984. Over the past 20 years, many more men have served in the new 10th than in the original 10th, so they would be a large market for rings such as this one. In either case, you can assume not many were sold with the emblem upside down.