The title refers to diamond gemstones with the highest quality, having, or approaching, the clarity, purity, and perfection of clear water. It is also used to describe an exceptionally beautiful young woman.
In the books, the Berbrooke men were used as comic relief and the Bridgerton girls were never encouraged to marry them or encourage them.
When Simon first comes home to be greeted by Lady Danbury she tells him of a party that she is hosting. While declining he pauses between certain words foreshadowing his childhood speech impediment.
The mansion under construction is Carlton House.
The song playing during the ball is a string arrangement of Arianna Grande's "Thank U, Next."