It took a little while, but it has arrived....
This is the Ernie Banks Diamond Die Cut card. It features a picture of Ernie Banks in the 1957 road uniform. That was the first year the Cubs wore a hat with a rounded C instead of a wishbone C. The '57 cap also featured white piping, which disappeared after one season.
I bought it about a month ago, but the seller didn't have the card in hand.He first had to order it off the Topps site, and then send it to me. I was a little nervous because I didn't know how long it would take. But my fears were unfounded and the card is now in my bulging Topps binder.
There is still one more Cubs Diamond Die Cut on my checklist, the Ryne Sandberg card that Topps added via their fan vote. As far as I know, the card hasn't been released yet. And when it is, I'm thinking it will be fairly limited and fairly expensive.