Male hormones tend to make roo combs lighter in colour than those of females---this is why a darker comb on a young cockerel will often lighten as he matures.
Pink or rose is too red, and would be disqualified. Mulberry to black is the standard. In general, the genes that dilute feather colour often also dilute skin colour, so your darkest combs will be on birds that do not carry diution genes: black, often white, partridge, red. Buffs seem to be the most affected with too light a comb. With cuckoo it isn;t dilution, but rather gene linkage that makes a dark comb difficult to obtain.
A orrect comb should look like the nut it is named for, a walnut. There are some gnarley combs that I could see being referred to as brain tumors, but not a correctly shaped one. As with all breeds, male combs are larger than female combs. Some females do have almost cmopletely flat combs,but the standard calls for the same walnut shape--most of mine have that.
Walnut combs are genetically a combination of rose and pea comb genes. There is an additional gene that occurs with some rose combs that causes a rough versus a smooth surface. I've seen silkies with both variations. I prefer the smooth. Ther is also a gene that causes points at the top of a comb. At one point the standard required them; they are now considered a fault.
I should also throw in that while I described the genetics of a true walnut comb above, traditionally silkies have instead posessed a modified rose comb, and not carried the pea comb gene. Tomorrow I'll try to find the site that has photos to show the difference in appearance. I have a few of the modified rose comb birds, but most of mine are true walnut combed birds.
