This prototype of the sterling silver Keepsake is missing the inscription for the Parker name and logo usually found around the cap band. It is a prototype by the fact that there is no inscription around the cap band as seen below, not even the country of origin.
Even more interesting is this pen has what appears to be a prototype flat cap tassie that I have never seen before on any other Parker 75. Instead of the normal four stacked rings, this one only has three and so shorter than normal. One thing I am sure, this tassie is not a BP or MP cap tassie.
The fact that this tassie is flat dates this prototype as pre-1970. But with the cap tassie being shorter than normal, it may imply this prototype is even earlier than the 75 itself. What I mean is that it may have been one of the test models prior to the grid pattern being selected as the first pattern to launch the 75.
To see how this prototype compares to a production model, follow this link.
Another interesting variant is found on the second prototype Keepsake as pictured below.
Like the above prototype, there is no inscription around the cap band. What is interesting with this one, however, is the use of dished tassies. In fact, there is a thin disc placed onto the cap tassie that has the numerals "75" etched onto it. This use of the dished tassie gives me reason to think this may have been a prototype of the INF Treaty pen in its pre-inscribed state. Whether or not those two pens had the same etched "75" disc is unknown to me.
I acquired another variant of the Keepsake which I believe is the same model as that used for the INF Treaty signing.
As you might notice, this one is interesting in that there is no inscribed ring near the open end of the cap to form a cap band. In fact, the Parker name is not in the front under the clip but rather in the back as shown in the close-ups below.
Interestingly, this Keepsake has a dished tassie implying that it was made much later than the original Keepsakes.
By coincidence a visitor to these reference pages wrote to me and described an identical Keepsake as this one. He wrote that his is inscribed with the name of a retired Parker employee and engraved as a date of January 1981.
With this information, it is my theory that these later Keepsakes were never sold as production units to the general public. Instead Parker kept these to commemorate events significant to Parker itself. This is quite appropriate as this use is exactly how Parker originally marketed the Keepsake model -- as a highly personal pen that would be used to inscribed significant events in one's life!
Yet another slight variation from all the above. This time the Parker name and other information is inscribed on the front of the cap, all squeezed into a small area. Also note that there is no ring forming a cap band.