Let’s start with the basics: Diamond is the grape's name. It’s a cross of Concord (a grape you probably know from Welch’s — juice and jelly) with Iona (a grape you probably don’t know, but it’s another cross with Catawba parentage.)
It’s mostly used for non-descript, fruity, sweet wines.
But winemaker Phil Plummer makes this beautiful pet-nat from it — …