The breeder that I receive my S grade CRS or Black Bee shrimp from Hong Kong has 4 white bands. Here is a picture of a S grade CRS:
However, I have also seen only 3-banded "S grade" CRS/Black Bee shrimps from other breeders in Hong Kong and in Taiwan though like you have stated Pedro.
Nice shrimps,
but I don't see "high grade". most of CRS are A some B, S has 4 bands, so none seen
One of Diamons is also nice, but bestly A grade.
S and above have to have solid Red/white/black.
I see some S around there in some of my pictures with some tiger tooth and v-bands. Pictures are not the best, but I can say the white and red are thick and no gaps or transparencies and they are 4-band shrimp.
Grade varies by country in some cases. At least that has been my experience.
Also, I have seen that females tend to loose some color when they carry eggs.