Instructions
Locate the Parker Pen clip. The shape of the pen clip is often the company symbol of an arrow complete with vanes or fletching. The tip of the arrow is pointed downward with the vanes near the top of the pen cap.
Look for the name "Parker" on the pen. It might be located on the cap, clip, or pen band.
Open the pen to reveal the ink cartridge. Parker makes ink cartridges specifically for their pens. The ink cartridge will bear the Parker company name.
Look for the "H" located on the gold of a Parker Pen. The George W. Heath Company did the gold work on early Parker Pens. They stamped an "H" signifying their company symbol on Parker Pens.
Reference your pen against the Parker Pen catalog. Their are collector sites such as Parker Collector which detail the older pens in the Parker line. Search through the catalog to determine if your pen is an authentic match to one of the many pens they have produced over the years.