Oooh, something I know how to answer!! That's a rarity for me!!
I've kept diamond doves for ages and you can normally tell the sexes apart pretty accurately from the pink eye ring - males have a much thicker eye ring than the females. Although young doves will all have the same thin eye ring as the females so if the birds you have are young, you may have to wait a while.
Also the males have a little ritual, they will bow their heads to the floor, coo repeatedly and fan their tails in and out whilst holding them bolt upright. Of course, the best way to find out is to give them a nest pan and see if they breed! Given the right food and housing, they breed very very easily.
As for the colours, I'm not so good with them but I'll have a look at your pictures and if I know anything useful I'll post it in a minute!