My way of verifying sex in angelfish

Here are my steps:

1. I keep males and female seperate...these are the ones that I am definitely, absolutely sure
2. I get two unsexed breeder sized angels
3. I place the two unsexed breeders and one sure sexed breeder
4. I wait and observe for a few days

Normally, the sure sexed breeder will nip at the unsexed breeder that is the same sex. Sometimes, the two unsexed breeders nip at each other which means they are the same sex and want to pair up with the sure sexed breeder.
If they all fight, try changing the sure sexed breeder with a sure sexed breeder of the opposite sex.

Here is a sample. The gold in the middle is the mature female. The platinum at the right side (near the female) is a male. The fish at the left, hiding behind the slate is a female. The mature female chased her away because she wants the male for herself.