Im curious. I always wanted to know what happened on this Bombay Hook Delaware Quarter when the letters look shaded gray color. Just look at the letters in the photos. Is this a Struck-Through Grease, or something else. I’m guessing worn die, post mint damage?
Those devices, letters are recessed into the coins surface. What happens is the coin collects debris, oils and just everyday circulation. This will cause those recessed areas to get dark and tone to a terminal black color. Those are some good photos by the way.
I’m not seeing anything unusual. As @Pickin and Grinin mentioned, these are incuse letters (recessed into the coin’s surface rather than raised above it). They’re liable to collect gunk from circulation, as he said.
