My first test is the colour. The imposter is almost red while saffron is rouille or rust. The red
are fuzzy and complex in shape, have no scent and tend to be longer and wider. But of course the real tell, without putting it into a liquid is the price.
I normally get saffron from Spain if I am buying it on trips.
When my friend (later trip) was buying the cumin for me, I warned her against buying it in an open market as all kinds of junk can appear there. She bought cumin seed only, smart, so she could see what she was getting and had it vacuum-packed. I love Mediterranean cumin.