Orange has become easier to make due to the understanding of where the colouration comes from. We are working with an orange HM line at the moment and its proving to be a very rewarding line.
ORANGE
Orange comes in many forms, this can be classed as burnt (a dark version) light (obvious) and polka (like nettys VT), these are what I've seen but there could be many more. There are also some that hold the orange genetic, these are called genotypes, where the betta will hold the hidden genes that will lead to producing orange. It all stems from the red loss gene (a gene that is missing the full 100% to produce red, thus giving a lighter version of red).
Its fairly easy to determine a genotype of orange.
EXAMPLE
Take a picture of the fish with a camera that has a good flash on it. You will see in different genotypes that:
1) The fins of a fish will be a mixture of dark red and lighter red
2) A fish that holds a high % of red fins and has a cambodian look to it, will have a white body rather than the usual muddy white seen in cambodians. The red fins should also hold a small % of lighter red in them.
Crossing any of these bettas will indeed give you some fry that will inherit the orange, which most of the time will give you variations of the oranges stated above. There is also a high % of fry that will carry the blue gene if the family line is less than 3 generations old, this is due to family lines and throw backs, giving a splash of blue/steel or green whether it be in rays inner or outer trims (inner = on the fins but next to the body. outer = on the tips of the fins, an outer trim is typical of what you would see in a butterfly betta) or as a scaling over the body as you would see in half dragon bettas. Working with the line will reduce this blue to a certain degree but not fully.
One of my recent spawns was created from an orange male hm and a orange hm female. The resulting fry are dark orange, red, yellow, yellow and black trim, white celophane and one wine mask (a colourless head and a red wine coloured body) really pleased with the conclusion but this is only F1.