So just to make sure I understand - if I were to breed my polishxorp roo to my salmon faverolle hen, would they have the potential to be diluted? Or no because the SF has no lavender gene?
Salmon Faverolles are not expected to have the lavender gene, so there should not be any diluted (lavender) chicks.
Is there a good book about chicken genetics I can read? LOL
Um, I'm not sure about "good."
There's one called Genetics of the Fowl, by H.B. Hutt, published in 1938.
Last time I looked, it was available to read for free on the internet.
But it is not easy to read, and some parts are not accurate (people have learned things since it was published.)
There are a few chicken genetics books that have been published more recently, but I have not personally read them, so I don't know how good they are.
There is some information here:
https://kippenjungle.nl/sellers/page0.html
It has links to a page on basic genetics, one that discusses some specific chicken genes, and one with a table of genes (tells a little bit about each gene.)
Since I was not a beginner when I found it, I don't know if it is actually a good starting point, or if it is written at the wrong level.
You can play with the chicken calculator here:
https://kippenjungle.nl/chickencalculator.html
I find it helpful for modeling the effects of genes: change the genes in the dropdown boxes, and the picture of the chicken changes too.
For lavender, find a box that says "Lav+/Lav+"
That tells that a chicken has the dominant not-lavender gene (capital letter because it is dominant, + at the end because it is the orginal form found in the wild jungle fowl.)
Change it to Lav+/lav to represent a chicken that carries the lavender gene (no change in the image, because lavender is recessive.)
Change it to lav/lav to represent a chicken that is pure for lavender, and shows the effect (the image changes from a red-and-black chicken to a cream-and-gray chicken.)
To model a black chicken, the top dropdown box gets changed from e+/e+ (the wild-type form that came from wild junglefowl) to E/E (Extended Black). Or you can change it to E/E^R (split for Extended Black and Birchen, which is what your half-Sebrights probably are.)
A black chicken with lavender (E/? with lav/lav) will be lavender.
The default settings, when you first go to the page, are the wild-type form of each gene (the one found in the wild Red Jungle Fowl.) They are marked with + (which is handy if I cannot remember what it said before I changed something!) All the others are mutations, with capital letters mostly indicating dominant genes and lowercase letters mostly indicating recessive genes. I say "mostly" because some genes are incompletely dominant (one vs. two copies of the "dominant" gene have a different effect), and some genes have many options that do not have a simple order of dominance (the e locus, top dropdown box with E and E^R and e+ and others, is probably the worst of these.)
With chicken color genes, I would say they fall into a few main groups:
--some affect how the colors are distributed on the chicken (in the chicken calculator, these include the first 5 dropdown boxes of genes, and interact in various ways with each other.) I find these ones to be the most confusing to learn about.
--some change individual colors (black becomes blue or white or chocolate, gold becomes red or cream or silver). Lavender dilutes black to gray and red/gold to cream. I find these ones the easiest to understand.
--some put white in specific places on the chicken, over-riding what the other genes are doing (barring adds white lines, mottling adds white dots, recessive white makes a chicken white all over.)
