m0useanswered grow question a month ago Purple is just extra flavonoids called Anthocyanins, they are fun and not very heat stable, more for eating from my understanding, some of the pigment goes into the trichomes and thats ok.
judge them like other plants, Pistil dry back, Trichomes, and bud density.
aorund 80% pistil dryback
Mostly milky trichomes with a scattering of clear and or amber in the mix
Good bud density and plant is drinking less water indicting its slowing down and finishing up.
If its al that, good to chop.
Also if you entering wet season and need to harvest a bit early also ok. better then bud rot and WPM issues, Clear trichomes still have tons of THC in them. cloudy and amber are degraded a bit.
With all outdoor plants I tend to give them a gentle washing "bud washing" to help dislodge anything that got stuck in them.
Good Luck!