Yes you are right about the colour and the directionality of the particular case of the first opal I showed, but this is a crystal opal, completely transparent and translucid, and the inner silica planar structure that reflects the light at various wavelengths can be visible by its refection. This gives you an effect similar to a “directional” reflections. But these are not fake, with pieces of metal inside, if that is what you meant by “not true”
When the stone has a deeper body colour (like white, pink, grey…) the reflections of light through the inner silica structure is richer, multiple orientations are mixed, resulting undirectional light reflections.
Also, I don’t think you can compare a black australian Opal with a crystal Ethiopian Opal. Of course, the former is much more valuable. In my opinion you can only grade opals within their families, a black opal from ethiopia is much cheaper than one from Australia, but it doesn’t mean it is a low grade, it could be a grad A fine black Ethiopian opal.
Please correct me if I am wrong…