I've tried them, and I didn't like them. They lack the beauty and depth of real ebony, and working them was unpleasant. I don't use them. I usually go with Maccassar Ebony, which has more color variation than most ebony, which as far as I'm concerned makes it much more beautiful, and it is also more avalible, so you can easily get quartersawn blanks. The more traditional ebony is pretty much impossible to get quartersawn fingerboards any more.
Light
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M.K. Gandhi