Inheritance: Unknown, probably autosomal recessive
Pigment change: Unknown
“Schimmel” is a nickname for a new color or phenomenon, yet quite unknown. Schimmel causes shiningly mottled unsymmetrical pattern. Much isn’t known about this color, mutation or inheritance but it seems that the pattern gets lighter in time. This color is extremely rare and few even know anything about it, partly because of the language barrier between European breeders. The name “schimmel” isn’t official since neither the color or gene has been recognized, not to speak of establishing.
The other reason why schimmel hasn’t spread yet, even though the appearance is very fascinating, is probably because the breeding seems to be hard. The pattern is hard to control and and is doesn’t seem to follow any rules or symmetry. The mutation is or was studied in Germany and/or Netherlands and it can be assumed that it may receive great popularity if the breeding broblems can be overcome.
German breeder Otto Lutz wrote about the subject, asking anyone with more information to contact. I encourage you to do the same: if you know someone who know what’s up with “schimmel”, I’d be glad to know. Please contact: firstname.lastname@example.org.
Source: Nymphensittich Spezial, Maj/Juni 2010, “Schimmel” von Otto Lutz