If you can wait, you will be able to see a change in color, in the overall plant.
The hairs will change color and recede back into the plant, but again as far as seeing the amber,
you most certainly can see it without a scope.
The overall shade of the plants will "bronze" up for lack of a better word.
The problem, or reason ppl say you can't see the change with your naked eye,
or the pat answer "get a scope dude."
At the first sign of red pistils, or amber trich. they're chopping plants down.
If you can't wait for a plant to mature, you'll never know what one looks like.
I wouldn't want to guess how many trics are on the average plant, but checking
100 trics out of 100,000,000 doesn't paint a clear picture for me.
Using a scope to look at trics IMO is ok if you harvest leaf by leaf.
Again, look at the Whole plant/bud she will tell you when shes ready.
Look for Zeus's harvesting guide. That guy is spot on when it comes to when to harvest.