Those stamps are subject to sulphurization (sp?). If that has happened to these tamps, then the yellow would turn a deeper color mimicking orange. Other than that, I would call them orange. The yellow color of those stamps is very yellow, and often duller than the orange.

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These are both the common yellow shade. Like most stamps that were in use for a long time, there were many printings and there are many minor gradations in colour between printings. The "named" colours in the catalogues are generally the extremes of the spectrum.

Here is a pic I grabbed off eBay that has a yellow and orange side by side:



Roy

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