The Parker 51 fountain pen is a classic writing instrument first put into production in 1941, when the company celebrated its 51st anniversary in business.
Parker made subtle and overt changes to 51 in the decades since the fountain pen was first introduced, although the basic design remains the same. Learning about style changes in the Parker 51 will help you date a pen and perhaps locate a collector's item, as these fine writing instruments are now considered to be.
Identify first-year 1941 models by the imitation jewels mounted on the end of the pen cap and the barrel end. The jewel on the end cap (tassie) is affixed to the top of the screw that holds the pocket clip in place. Almost every first-year model was engraved with a single-line imprint around the end of the cap barrel near the tassie.
Parker 51 pens with two imitation jewels--one on the cap and another on the end of the pen barrel--remained in production until 1948, although very few were made after 1946. If there is no Parker imprint around the end cap and the pen has two jewels, it can be dated most likely between 1942 and 1946.
Identify pre-1947 Parker 51 fountain pens by the distinctive blue-diamond mark on the company's trademark arrow pocket clip. The blue diamond was eliminated on pens made from 1947 onward.
Know that sterling-silver Parker 51s also predate 1947, because this model was discontinued before the company eliminated the blue-diamond mark on the pocket clip.
Recognise 1950s models by identifying different pens in the Parker 51 series. These include the stainless-steel Flighter model; the Heritage, which was manufactured with solid 14K-gold trim; the solid 14K-gold cap and trim Heirloom; and the Presidential, which featured a cap and barrel machined from solid gold.
Parker 51 fountain pens with matching ballpoint pens or mechanical pencils date back as early as 1946, the year Parker first began manufacturing sets.
Identify 1960s Parker 51s by the brightly coloured plastic barrels and caps. Moulding products out of plastic was in vogue during the 1960s, although the plastics have not held up well in the last four decades, so plastic Parker 51s that are in good condition are something of a rarity.
Parker 51s utilising ink cartridges date to the 1970s, as the company began offering cartridges as an alternative to refillable liquid-ink pens with "Vacumatic" technology to hold the ink in place until the instrument was in use.