Coach Serial Numbers
Serial numbers were introduced in the mid 70s, and every bag had its own unique serial number. These early serial numbers had 3 digits followed by 4 digits (101-9090). This changed to 4 digits followed by 3 digits in the late 80s (1010-909). In 1994 letters were introduced into serial numbers. The middle number in the first set of 3 digits indicates the year of manufacture (A7B-9990) = 1997. The serial numbers were usually hand-stamped and they used a small press with rotating wheels that they could advance to the next number in the series. Often numbers would be a bit uneven and a lot of times you can even see a horizontal spacer line or the edge of the next or previous number in the series.
(There are some early to mid 70's bags that have the Coach Creed and an obviously glued-on serial mark that was added to the bag after it was manufactured. You can see that the serial number was applied to a leather strip and then placed under the Coach Creed in these early purses. Sometimes the strip with the number would come lose or fall off leaving just a strip of bare leather where the number should be.)
The 7-number serials were phased out beginning in 1994, and replaced with an alphanumeric serial which had three digits representing the factory, year and season, and after the hyphen, the four digit code for the bag model. For example K4M-5130 would be a Station Bag (5130), made in 1994 (the number 4, in the first set). The K & M are factory and manufacturing codes. So every single Station Bag made in 1994 in that particular factory could have the identical serial number. And some popular bags were made in more than one factory so the same style number could have different prefixes on different bags.
Coach did NOT add the fourth digit in the serial prefix until it was necessary to prevent year repetition, in 2004.
Thus, the pattern goes like this: J4J = 1994, J5J = 1995, etc... then J0J = 2000, J1J = 2001, J2J = 2002, J3J = 2003, but then they go to four digits J04J = 2004, J05J = 2005, etc... So a bag made in 1996 would have a prefix of x6x-, but one made in 2006 would show x06x-.
In 2005 and 2006 even more codes were added although the year code is still in the same place in the sequence. Bags made just for the Factory Stores will now often have the letter F before the style number. Some bags such as the 2006 Legacy line can have as many as ten digits in the serial number, five on either side of the hyphen. And beginning in 2005 some style numbers began to include letters as well as numbers until Coach decided to expand the style number to five digits.
Thanks to all the posters at Ebay's Shoes And Purses forum and other boards who compiled all this great information!