It is quite difficult to say -for sure- if a given pearl is color treated or not, especially if the dye/bleach job is a good one. The obvious ones -those lime-green or fuschia-pinks and even jet-blacks- are rather easy to detect, but some goldens, and cocoa colors are quite hard to discern!
There are naturally colored golden baroques of course, but why is it hard for you to find those? Hard to say as well...you are not approaching the correct vendor, I guess.
The pearls in your photos do strike me as South Sea pearls.