To the top.
You got any pics?
There's just something about Amboyna Burl. I had a custom, 1 of 1 cue made in the Philippines by a well known cue maker. Loaded with Ivory and beautiful veneers. The grip area was all Amboyna, just like yours, and it did the same thing. I was told it had something to do with the glue used. I've seen several cues like this that have all done the same thing. Personally, I think the remedy is to "section" the grip area into three pieces, causing less stress on the wood.
I absolutely love burl woods, and, along side of firey Cocabola, Amboyna is my all time favorite.
Good luck with your sale!:thumbup: