As the title says. Creating gem windows using the DFHack planner interface won't add any value to the room it is built in, both when letting the program choose or using the filter. Whereas using the vanilla interface to use lastest materials, closest materials or manually select the gems will properly add value.
To replicate :
- Create two small guildhalls and assign a legendary broker to see the exact value
- Dig/create gems and cut them if needed
- Build gem windows in one using the DFHack planner and the vanilla interface in the other
- Read the values of both rooms