Picture below shows Orange as found in France
©Fanch Gourvès - France
This bird has an intense peach-rust-orange color on the
body, head and wings. No violet color on head, neck or chest areas. Bill
coloration is light. The main
distinction is that they should have a white neck ring & the primary flight
feathers are white (upon close inspection faint dilution is found - often a
microscope is needed to see the dilution). The eye color is a
chestnut red (see pic under Orange Pearled). Undertail bar is
diluted. Orange is the
"dilute" of Tangerine. The undertail coloration can be a determining
factor for a bird being Orange (see pics below).
Note: the original Orange birds which were imported into Canada & then eventually into the US all had the "pure" white neck ring - there were not any grey or smoky neck rings as seen in today's Oranges.
These pictures show the undertail bar coloration of an Orange & also in comparison with the undertail of a Peach. Tangerine dilutes the dark tail bar to a silver/grey, when the "dilute gene" is added to produce an Orange, this silver/grey dilution is diluted even further.
Peach (R) & Orange (L) Comparison - Note the
different neck rings, the darker undertail bar is also seen in the Peach.