Charcoal is a deep grey that anchors a colour scheme with ease. You'll find it as 100% cotton Kona by Robert Kaufman, 44" wide, cut from the bolt in ¼ yard steps to suit your pattern. For a coordinating thread, try Aurifil 2630 Pewter.
Looking for the coordinating Aurifil Thread? Try Aurifil 2630 Pewter
Solid color Kona cotton from Robert