The page confirms that it is a 100% ceramic dial (both black and white parts) and it shows that he went through five different trials before getting it right.
The first time he tried a black base ceramic with white ceramic overlay but the white was almost transparent and let the black bleed through.
The second time he went with white ceramic with black ceramic overlay but the white ceramic had poor conductivity so he couldn't get the black to transfer uniformaly.
The third time he changed the white ceramic material and tried again with only marginally better results with the black ceramic adhesion.
The fourth time he used the same material with better results but had issues with the numbers and the color tones not matching Omega gen colors.
The fifth and last time he tweaks the white and, from his perspective, he nails it with the right color tones and perfect adhesion.
He then just shows each one side by side. If you look at the last picture, he puts the first try against the final version. He points out the difficulty with getting the numbers at 6 and 18 to look right but he believes it is a perfect match to the Omega gen. He goes on to say that he only has about a 10% rejection rate during QC.