The scatter node "Scale" parameter controls how far light seems to travel through the volume of the material before losing a specific fraction of its original energy. Unfortunately it doesn't do so using an intuitive parameterization. When you increase the Scale, you decrease how far the light goes. When you decrease the Scale, you increase how far the light goes. The admissable values for Scale are anything above 0. (If set to 0, the equation breaks down and no light comes out at all) The original research paper that led to the Scatter node algorithm in Poser included real-world measurements of various materials. If you set the Scale to 1, you will reproduce those measurements exactly.

But as I said, real marble or jade don't follow one single and unique "scale" so it's acceptable (and even mandatory in some cases) to change Scale to be more or less than 1.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)