While I agree that margins are everything, especially with Woodblocks (as to obtain an exceptional margin means that you had to sacrifice the stamps beside it)
I am talking about a error of colour woodblock.
They only occured as
1 per sheet, in the same position and so are very rare. Probably less than 1 per sheet as they don't come in all the colour varieties of the woodblocks.
My references on woodblocks (Stevenson, Jurgens and the Sir J Maxwell Auction Cat) indicate how rare these stamps are.
Stevenson notes that there may have only been 100 left of the Red colour error. Only about 1,100 were ever printed out of the 125,000 woodblocks in red. As most were used to wrap papers in, they were quickly used and tossed. Maxwell had 11 in his astonishing collection. (I checked the photos - this one being offered isn't one of them).
Stevenson notes that there are
only 2 mint examples existing of the colour errors in red.
While I can accept that Feldman may offer 20 woodblocks a year - that's reasonable, even eBay sells about 2 a month -
they couldn't possibly be selling 20 Colour Error Woodblocks each year. I'll have to check them out!
I am working on a pet project to catalogue and print every existing Woodblock I can get a good photo of. So far I have photos of about 200 of each woody and about 2,000 normal issues.
Woodblocks are one of my passions.
