Hermes did not use any stamps between 1922 and 1944. The coding system was introduced in 1945 with the "Blind Stamp" consisting in alphabetical letters for each year of production. This period ends in 1970 with the addition of shapes (circle first and square after) surronding the letters. From the year 2015 onward, Hermès has been using a more traditional system feautiring a L LL NNN LL format. The first letter in the string is the classic Date Stamp, and the following letters and numbers represent the Craftsman Stamps.