Panerai Serial Numbers, Year Designators & Production Numbers
Serial numbers on the back of current Panerai watches take the following form:
BB97xxxx or BB98xxxx
For the first number, OP65xx, there has been some disagreement as to it's meaning, however it would appear to designate the number of the case of the watch (regardless of dials etc.). The case number on seemingly identical watches can occasionally change from year to year, presumably because of some microscopic change, or perhaps the case comes from a different manufacturer. Here is a table of watches seen so far.
The second number is the individual watch number that started in 1997 with BB970001, and is steadily increasing. For the year 2000, numbers of 101xxxx are not uncommon.
In the last number 'Z' represents the year designator. Each year's product gets a letter
(no letter): 1997
and the final 'n of m' is this watch's number out of the total product for the year.
So B:123/500 designates a watch made in 1999, which is number 123 from a total production of 500.
These production numbers usually cover all watches of a particular style, regarding of dial colour or finish. So for instance for the C year designator 40mm automatics are marked xxx/5000, and this 5000 covers white dials, black dials, blue dials, bracelets and straps.
The Vendome reference section shows production numbers for the various years where these are known.
There are also some complete tables on the millesimation page.
2002 Serial Number Changes
In mid-2002 some watches started to appear with serial numbers of PB50xxxx instead of BB10xxxxx. As far as I can make out, this is a change to the numbering systems. So far I have seen GMT and power reserve watches with these new serial numbers.