I’m assuming it is hinged, based on the CV provided in the photo, as neither the listing or cert states the gum condition. I would estimate the retail…

What is the gum condition? In order for 491 to be authentic it must have no watermark. Also 491 only comes in carmine color, and this image looks more…

Brookman is the go-to I usually use for sheet values. I treat their pricing like a Scott catalogue value. I would aim to get anywhere from 10%-50% cat…