Modpack version
1.7.5

Issue
Tinker's tool with diamond upgrade does not change mining level after using sharpening kit.

(I had wooden + stone pickaxe and I upgraded to copper pickaxe head, applied diamond (that I found while exploring) then used quartz sharpening kit, and the mining level was still copper.

Edit: Seems like the level is 1 step down. as using iron sharpening kit will make it certus mining level

Thank you for the report, I will investigate the issue.

This is a side-effect of me overhauling mining levels, and it doesn't look like it can be fixed without a rewrite of the Tinkers API, so I'm afraid you'll have to live with it :)