Dark male x Partridge female = 100% Dark (hiding Partridge) males x 100% Dark females
Partridge male x Dark female = 100% Dark (hiding Partridge) males and 100% Partridge females
Dark male (hiding Partridge) x Dark female = 25% Dark males, 25% Dark males (hiding Partridge), 25% Dark females and 25% Partridge females
Dark male (hiding Partridge) x Partridge female = 25% Partridge males, 25% Dark males (hiding Partridge), 25% Dark females and 25% Partridge females
Dark males (hiding Partridge) will look like a Dark male because the Silver gene is dominant over its alternative the Gold gene. So heterozygotes for Silver and Gold look like a Dark. However, the gold can sometimes 'leak' through in the plumage, particularly on the wing and around the neck and saddle hackle. This is not always a certainty and sometimes Dark males (hiding Partridge) can appear to be a pure Dark male. In this instance the males genetic makeup is only revealed when some of his daughters turn out to be Partridge even though he was mated to a Dark female. At first, the results of these crosses may seem odd but if we think about the inheritance of sex-linked genes it makes sense. Remember males can possess two copies of either the Silver or Gold gene or a combination of both genes whilst females can only possess one of the alternatives. Because females can only posses one Silver or one Gold gene they are called hemizygous and not heterozygous.
This is because the Silver and Gold genes are located on chromosomes which determine the sex of an individual, termed sex chromosomes. The two sex chromosomes in chooks are called Z and W. Females have a Z and W (ZW) chromosome and males have two Z chromosomes (ZZ). The W chromosome in females is very small and does not carry the same genetic information as the larger Z chromosome. In humans we call our sex chromosomes X and Y and the pairing of these chromosomes is reversed between the sexes. So human females have two X chromosomes (XX) and males have an X and a Y chromosome (XY), with the Y chromosome being small and carrying less genetic information.
We call the sex possessing two copies of the same sex chromosome the homogametic sex and the sex possessing one of each type of sex chromosome the heterogametic sex.