Wahl-Eversharp Gold Seal
Wahl's use of the double check mark dates back to the 'teens, but it was in 1928 that it was first applied in the form of an inlaid metal disk, called the Gold Seal. These seals denoted Wahl's top of the line products, and were a response to Sheaffer's White Dot, which was similarly placed.
It is not uncommon to find Gold Seals drilled through with a fine hole. At the end of production, remaining stocks of Gold Seal pens and pencils were sold off at steep discounts, but without the Gold Seal lifetime guarantee. The seals were drilled to indicate the cancellation of this guarantee, and many pens were also assembled with special warranted nibs and conventional sections rather than Gold Seal nibs and Personal Point sections. The warranted nibs did not bear the Wahl-Eversharp name, but are easily identifiable as Wahl products by their distinctive imprints. Most are numbered either 5 or 7.
A drilled Gold Seal does not normally have a significant effect on value. Collectors seem to be more concerned with the nib, preferring pens with Gold Seal nibs.