sexing german blue rams?

[TampaBayBucs]

how can you tell the difference between a female and a male GBR? i have 4 and i was wondering

 

[Helena21]

males- first 2 rays on dorsal fins are longer than in the females

females- pink belly in breeding season, speckles in big blue spot

 

[Pure]

Also, at a mature age the males will be noticably larger.