Maker and Black/Dark Crystals

The answer is yes, they work like Chaos. Black affects non-AP, Dark affects AP only.
They also can affect all of those stats that are possible on the item itself, and I believe it activates AFTER other crystals, so you can make it hit something that you just added with another crystal. They can range from their highest number +/- and in between, ie. a lvl 3 Dark can add anywhere from +5 to -5 on STR, DEX, LUK, and INT.

I used lvl 2 Dark and a lvl 2 Power on a pair of pants, the Power added 3 str, the Dark took away 3 str, and it ended up average.

Doesn't a stimulator prevent stat losses, which therefore means that -3 STR would have never happened and could have been a +6 STR pants instead?