Starting in the mid-1920s, leading US pen manufacturers competed in offering increasingly comprehensive guarantees on their top-line products. At first these guarantees were reflected in model names such as Lifetime, Endura, and Eternal, but it was not long before some companies created special symbols to denote their guarantees. The best known of these were Sheaffer's White Dot, Parker's Blue Diamond, and Wahl-Eversharp's Gold Seal.
As generous as these guarantees could be, few will do much to help vintage pen owners today. Most were valid only for the pen's original owner, and many have been rendered moot by the disappearance (or, in some cases, reorganization) of the companies involved. In some cases, the guarantee applied only to the nib. And lest you be tempted to send in an old pen to its original maker for service, be warned that you may not get it back: most companies that still do honor those old warranties do so by sending out a replacement from their current production. It's not just pens -- few manufacturers of any product now retain stocks of repair parts for products more than a few years old.