carve (something) in stone
To make something permanent and incapable of being changed, typically a plan or idea. We might get brunch next weekend, but we haven't carved anything in stone yet.
carved in stone
Permanently fixed or firmly established; incapable of being changed. Often used in the negative. The deal isn't yet carved in stone, but we're confident it will go ahead as hoped.
carve something in stone
Fig. to fix some idea permanently. No one has carved this one approach in stone; we have several options.
carved in stone
and engraved in stone; written in stoneFig. permanent or not subject to change. (Often in the negative.) Now, this isn't carved in stone yet, but this looks like the way it's going to be. Is this policy carved in stone, or can it still be modified?