Getting gray chicks from black hen and porcelain rooster

[I Like Turkeys]

I have a mixed hen who i’ve hatched 13 eggs from at this point. She’s black with gold leakage and the father to all chicks is a porcelain d’uccle. Most of the chicks have hatched out black with varying degrees of gold leakage, but some have hatched out gray instead of black. I am wondering how this is happening.
Here are photos of the parents:

I do not think the gray is coming from the lavender gene the rooster possesses, as the chicks are too dark for that to be the case. They are still visibly not the same level of black as their mother though, who i’ve inspected several times and can confirm she is just black.

I have photos of the chicks as well, to show the differences in color.

Black chicks:

Gray chicks:

These two are very young, but the one on the left is considerably lighter already, and i’m not sure why:

I am very confused for how this is happening. Admittedly, I don’t know much about genetics, and didn’t think there were any genes that caused gray feathers besides the blue and lavender genes. I know the rooster has the lavender gene, i’m not sure if he could also have the blue one or if that is what is at play, but the hen visibly shows neither. If anybody knows why some chicks are coming out gray, i’d like to know.

 

[nicalandia]

The grey chicks are clearly diluted by Blue(Bl/bl+), it's clearly coming from that rooster if he is the only sire.

 

[I Like Turkeys]

The grey chicks are clearly diluted by Blue(Bl/bl+), it's clearly coming from that rooster if he is the only sire.

Thank you! Is it common for porcelain d’uccles to have the blue gene? I was under the impression porcelain d’uccles have the lavender gene, and that therefore he did as well. Would he have both or just the blue gene?