These are "Rusty Duns", from left to right, pale rusty dun, medium rusty dun, and dark rusty dun;
This is described as a blue dun hackle which looks as if it has been sprinkled with rust, usually a reddish-gold colour. The colour should look as if it is painted on the blue base. Brassy dun is also used to describe this colour where the colour is more yellow.
Hackles of this colour were very rare indeed and highly prized.
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