How To Breed Platinum Gouramis?

Does anyone know how to breed the color for a platinum gourami from something like a blue gourami or other trichogaster trichopterus?

 

They are the result of years of linebreeding.
Just like opalines, gold, blue gouramis all come from the natural three spot.

 

What color is the natural one?

 

What color is the natural one?

Threespot = blue / some more silverish.

 

So I should just buy a platinum gourami. I want to breed it with a lavender gourami.