Quote - How much you suppose one slab costs?

 
It varies outrageously. Slabs are usually sold by bid in an auction type format to cabinet makers, especially the top quality ones.
For finished use, the most expensive marble countertop I ever installed was a translucent green Cappadocian marble that cost $625 per linear foot. It wasn't in my house, I can promise you that :lol:
Granite is the most expensive, I believe, at least in the finished form, because it is so difficult to cut and work it.

Not familiar with Onyx, it might be more...or less than marble.

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