A Bekko is a white fish with black Sumi.
Criteria for a good Bekko is as follows:
The head must be as clean/white as possible.
The Sumi markings must be well defined and should be lacquer black and deep.
The Sumi must be in balance and well distributed over the whole body.
The modern bekko has much less sumi as the old style Bekko.
The white should be clean and snow white, without any specks.
As with all varieties, it should have sharp kiwa, good body shape and be elegant.
I have noticed that no breeder in Japan breeds with Bekko anymore, and I wonder if the Bekko as separate classification at koi shows, will exist for much longer.
The most bekko's currently available from breeders, are Sankes that lost it hi(red)
In these cases, it is common to see some indication of old hi, which will be a demerit when judging a Bekko.
Herewith one of my Bekko's, 13 years old, large, fat, and as tame as can be.