My first fountain pens were made by Parker. They made a variety of different styles over the years, which makes them fun to collect–you can see how tastes changed over the years, and how the technology improved (or at least changed).
Parker also has usually had a date code on their pens. This helps know year of manufacture. This mark is usually small (only really legible under a magnifying glass) around either one of the end of the pen or the cap.
For pens produced during the Eighties and Nineties, they used a rather interesting system (this may have continued into the Twenty-First century, but I personally can’t confirm). The year of the decade is noted by the phrase “Quality Pen.” It lines up like this:
Year of Manufacture
The year of manufacture was based on either another letter, or a Roman numeral. Like the earlier Vacumatic date code, it seems to be the reverse of what one would logically expect, until you understand a practical reason: each quarter, they would remove a mark from the die. So, going from fourth quarter (either an “E” in the Eighties or “III” in the Nineties) to the third quarter (a squared off “C” or “II,” respectively) would involve knocking out a line.
Quarter of Manufacture
Let’s take an example: I have a Parker 75 with a date code of TE, indicating it was produced in the first quarter of 1985. My Sonnet was produced in the first quarter of 1994, with a date code of “IIII.”
It’s a handy bit of knowledge that can help gauge the age of a pen.