If you are talking about a USA made Aristo then they were made in 1950 but it was the last year of production. So if you had a stray that had a 1951 stamp then that would be rarer.
See...... http://www.mr-razor.com/Rasierer/One-Piece%20solid%20guard%20bar/1948-1950%20Aristocrat%20U.S.A.jpg
Steve