Buff is complicated. In playing with the chicken calculator lavender x buff gives solid black. So I guess it depends on what genes the buff carries. I am sure one of the genetics experts, such as tadkerson, henk69, Sonoran Silkies, or Icelandic, could provide a better explanation.
you left me out of that Lot... But I help him out..
as previously said, Lavender is actually a solid black bird that is modified by the recessive gene lavender, Buff genotype is complicated but is well known at this moment..
so lets try it..
Lavender genome is
E/E = Extended Black in Homozygous form
S/S = Most are Silver Based but they can also be gold based(hiden by extended black)
lav/lav = Recessive lavender, one copy cant express lavender, you need two...
co+/co+ = wildtype non columbian restricted,
Buff genome is
eWh/eWh = most Self Buff Birds(completely orange no black shown) are Wheaten because of all of the allele this is the least to express black pigment which is bad for a self red/orange/buff/cream birds
s+/s+ = they are gold, they would be self white if there were Silver based(food for thought, I bet you didnt know that)
Lav+/Lav+ = wildtype non-lavender Black/
Co/Co = Columbian Restrictor, dominant, very little effect on Extended black , but it may have some on heterozygous Extended black like
Buffs have other Powerfull restrictors, maybe Db and Mahogany combined with Dilute and other red diluters...
so What would a cross of them look like?
E/eWh = Extended Black Heterozygous, chicks will hatch solid black with cream underbelly
S/s+ = if they are S/s+ the males will have yellow/lemon hackles, breasts, if they are s+/s+ the color will be orange instead
Co/co+ = this will allow for some ground color(yellow or orange/red) on the hackle saddle and breast of the adult birds
Lav+/lav = this will not allow for lavender to be express as it needs two lav genes
