In the beginning of the first chapter of The Adventures of Tom Sawyer by Mark Twain I read:
The old lady pulled her spectacles down and looked over them about the room; then she put them up and looked out under them. She seldom or never looked through them for so small a thing as a boy; they were her state pair, the pride of her heart, and were built for “style,” not service — she could have seen through a pair of stove-lids just as well.
So what does state pair exactly mean and what is the etymology of this collocation?
The OED records several shades of meaning for “state” as having high status and accompanied by suitable pomp. These are mostly obsolete and survive in usages like “a state dinner held at the White House.”
So the “state pair” of glasses is a ceremonial pair reserved for special social occasions.