This was wrote by MacH AKA Stoner, it’s very informative .
Ya it’s a little long but not bad.
Hope this helps
Keep an eye on those trichomes. What a lot of white hairs mean, or could mean, is new calyx/bud/pistol development. In other words the buds could still be growing and swelling. This is why some people wait for nearly 100%, or actually the full 100%, of the “hairs” to have turned the orange/brown before they actually harvest. But this might be a bit too long for some strains and too many of the trichomes may have degraded to amber and this might mean couch lock or a too sedative like of a buzz. So the only way to be sure is to watch those trichomes.
Yup 2/3rd to 75% of the hairs (pistils) browning/amber is a reasonable indicator of when to more closely monitor the resin glands/crystals (trichomes).
Also a point of note, the “hairs”, the pistils can actually be different colors depending on the strain, normally white to off white when fresh, but many can be yellow, red or purple and much if this color may be retained when they shrivel and dry, but no matter the strain, these hairs will turn much more brownish when they shrivel and dry.This is why you may have heard about orange haired, gold haired or blond haired back in the day, and might see some strains with bright red or purple hairs in photos nowadays. Some colors can show in the resin crystals as well.
So normally amber is not a word applied to the hair color, lol. Amber is generally used to describe the trichomes, even the type that do show some other colors.
However the percentage of the resin glands/crystals (trichomes) to have turned amber should be much less to avoid couch lock.
Ideally you want 100% of the resin glands/trichomes/crystals to have turned from clear to cloudy/milky white.
Depending on the strain, you may want some of the resin glands/crystals (trichomes) to have turned amber, as especially with some sativas, if not enough of the trichomes have turned amber, some people say they get a little anxious or maybe even a paranoid kind of high. And so with these you might need at least 1/4 amber or as Latewood said, 1/3 to 1/2 amber trichomes.
Hope this clarifies some things.