I recently installed an ebony block on a stock I am working on, and when I trimmed the last quarter inch off the end of the ebony block after it was installed, I noticed a small hairline crack running diagonally across the face.

I wicked some CA glue into the crack and clamped it tight.

Will that stabilize the crack or do I just need to cut it off and start over with a different piece of ebony?

I don't know what CA glue is but ebony is oily and you need to de grease it first before anything will stick to it. I would start over.

Cyanoacrylate or super glue.

There are much, much better materials to use on porous surfaces and fill gaps than CA glues. But - if the stock is not yet finished why not get a new piece of UN-cracked ebony.

Thanks. I’ve got another piece, so I think ill just cut it off and start over. Would rather do that than have problems down the road.

A do-over sounds like a waste. Superglue 'gel' the crack. Quickly work it into the crack with a toothpick, carefully scrape of the excess with a razor blade after it hardens.

Since ebony is an oily wood, I would recommend washing the crack out with acetone prior to gluing. Then, after it has dried out, use the CA glue. Clamp overnight despite the fact that it cures up fast.

Its a good idea to degrease Ebony in the crack..i use black or matching glass bedding compound.