Very easy to sex visually and excellent beginners bird.

There are 3 things to look for when sexing Zebras: Cocks have bright Chestnut ear coverts lacking in hens. Both sexes shows the tear marks.

Cocks also have the Black chest bar (cock left)

And lastly cocks also have chestnut flanks (cock left)

No given there are some 18 mutations available in SA one needs to take them in consideration when sexing birds as it's not always that obvious what genes the birds are carrying so I will cover those that alter the "sex-identifiers" :

In the Black cheek mutation the cock's cheeks and flanks are black as apposed to chestnut

This goes for the hens as well (not the best example) one of only 2 mutations where the hen has a cheek patch.

The other is the Grey cheek which I don't have a pic of.

In the Isabel the cock looses the breast bar completely.

Also in the Penguin. This one is Black breast Penguin so a bit of colour does show. This bird got white cheeks, as it is also a Black cheek and the Penguin can't express black thus it's white.

In the Orange breast the black breast bag is replaced by an orange one.

And lastly in the Black breast the hens lack the teardrop.