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 on the red side, which would be 454. Can you provide an image of the back side dipped in watermark fluid? 491 generally needs to be certified as the watermark for these issues can show just a tiny fragment along an edge. 

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 to be $2,000 based on a very similar example that sold for that 11/15/23 in the Kelleher auction.

Hi My Fellow Stamp Collector

It is always funny to hear from other Stamp Collectors asking about the value of any given stamp. I guess more so when it comes to asking about a more uncommon stamp. The seller must determine what the minimum value of any stamp that they wish to sell. But at the end of the day it is the buyer that offers what they are willing to pay for a stamp. Anytime there is a possibility of a stamp that is cataloged in the thousands of dollars you have to have it certified as a seller does not want to invest their money in a One Dollar stamp after you claim that it is a rare several thousand dollar stamp. All buyers want to buy a rare stamp at cents on the dollar but the seller has to be held to the fire if they claim a stamp as a rare stamp. I take the Scott’s Catalog values and divide by 4 or 5 and offer accordingly. Using auction sell prices are another way but it is not the best way to get top dollar for your prize stamp. Values tend to be set by interested buyers as that is who will pay you for your stamp. Stamp condition, centering, gum condition, and so many other issues also effect the value. 😉