There's only one way to tell and that's with a jewelers scope or a really good camera, your looking for trichome colour and then it depends on what type of high you want, these will help
This one isn't anything you need to know, I just find it interesting
Turn off the light and use flash so you can get a clear photo. But yeah phase23 is right best way is jewelers loupe. I go by at least 70% orange pistils