A classic (and uncommon) embossing error on an early and crude CD 106 Hemingray. These of course are supposed to say 'MAY 2 1893' but the 2 is obviously missing on this one. Some say it might have been engraved before they knew the exact date that the patent would be granted, so they just included the month and year. Interesting theory, but I would attribute it to 'human error' myself! (The embossing is highlighted with paint if you wonder why it looks strange...)
This [id=162494882; Near Clear one] is from the same mold!!