Extraction of stones in the cave.

[Vanokillerskz]

I removed the clothes, nothing has changed.

Are you saying that with masonry 25, without quarryman/miner credos and (can't run the game now to confirm, but I think some of the skills like tunneling are adding to the q of the stones now) tunneling skills you are getting quality above 25???

at the time of discovery, skills were learned

[MagicManICT]

Tunneling, Metallurgy, and Deep Artifice don't add to quality, of that I can be sure. They add to the chance to smelt into bars. Nothing adds to the quality. Masonry hardcaps. It's possible to lose Masonry (temporarily) via injury, specifically concussions.

I'm not looking at your character sheet because you haven't shared it. I can tell you there obviously isn't a bug here, but you don't understand a part of the game, and we're willing to help explain what the issue is, but we need to know details to explain why there's a difference, otherwise we're just making random guesses.

[Hrenli]

Tunneling, Metallurgy, and Deep Artifice don't add to quality, of that I can be sure.

Their ingame tooltip says otherwise (but about ore, not entirely sure about stone).

[MagicManICT]

If you refer to the phrase "slightly better ores," it is referring to the probability of smelting into a bar increases. It goes from a base chance with none of the extra mining skills to 2x the base chance (if I recall right) with Deep Artifice.