of the first water
Of the finest quality, as in That was a play of the first water. This idiom refers to a grading system for diamonds for their color or luster (compared to the shininess of water). The system is no longer used but the term, used figuratively since the early 1800s, has survived it.
Words nearby of the first water
of one's own accord,
of service to someone, be,
of sorts,
of the devil,
of the essence,
of the first water,
of the kind,
of the moment,
of time and the river,
of two minds, be,
of-