Maker and Black Crystals/Dark Crystals

I was just about to make a thread like this.

I've been thinking that dark / black crystals can alter stats by a range of 1 to 1, 2, 3, or 5. I used an intermediate dark crystal on a 1 str 3 dex shoe, and got it 0 str, 2 dex, which supports this theory (range of 1~3, happened to land on 1). Is there anything definitive on exactly how these work?

 the shoe

your assumptions about black crystals are wrong.
dc affects AP stats. bc affects everything else except AP. #4 & 6 are correct.