Budgerigar colour genetics

The science of budgerigar color genetics deals with the heredity of mutations which cause color variation in the feathers of the species known scientifically as "Melopsittacus undulatus". Birds of this species are commonly known by the terms 'budgerigar', or informally just 'budgie'.
Background.
The wildtype (natural-coloured or wild occurring) budgerigar's color is called Lightgreen. The feathers of most parrot species, including budgerigars, contain both a black type of "melanin" named "eumelanin" along with a basic yellow pigment named psittacofulvin (psittacin for short). Some other parrot species produces a third pigment named advanced-psittacin which enables color & tones ranging from oranges, peaches, pinks to reds. When these feathers are exposed to a white light source, such as sunlight, only the blue part of the spectrum is reflected by the eumelanin granules. This reflected blue light passes through the yellow pigment layer, resulting in the green colouration known as "lightgreen" in only the budgerigar and/or "green" in any other naturally green coloured parrot species.
The many color variations of budgerigars, such as albino, blue, cinnamon, Clearwinged, the various Fallows, Grey, Greygreen, Greywing, Lutino, Mauve, Olive, Opaline, Spangled, Suffused and Violet are the result of mutations that have occurred within specific genes. There are actually at least thirty-two known primary mutations established among budgerigars. These can combine to form hundreds of secondary mutations and color varieties which may or may not be stable.
As is true with all animal species, color mutations occur in captivity as do in the wild. This has been demonstrated when captive-bred budgerigars have developed mutations that had only been previously recorded amongst wild populations.
Classification of mutations.
Basic groups.
Each of the thirty-two primary mutations belong to one of the four basic groups of mutations classified in parrot species genetics:
Dominance relationship.
These mutations are inherited through one of the following dominance relationships.
History.
In the first few decades of the 1900s, especially in-between World War I and II, the keeping and breeding of the budgerigar had become very popular all around the world. Consequently, various mutations occurred and were soon established during this period.
Notes.
It is possible that the Greywings mutation survived as the ancestor of all actual Greywings. However, it could be that the mutation lay dormant in asymptomatic mutant specimens until it was re-established between 1918 and 1925. Blue Greywing specimens were produced later on in 1928.
It is possible that all Suffused mutation specimens and their varieties are descendants from the first captive mutant specimens. This would mean that Suffused is the oldest sudden captive-bred color mutation of the Budgerigar species.