How Not to Get Cheated With Gems?

These are a few examples of real, natural gems which are passed of a blue sappires, emeralds etc.

Kyanite looks very much like a blue sapphire but will cost about 0.01 % of the cost of a similar blue sapphire.
https://www.mineralminers.com/images/kyanite/jewelry/kyanite-earrings.jpg

https://4.imimg.com/data4/KD/QL/MY-1909048/emerald-cut-blue-kyanite-stone-500x500.jpg

https://www.orissagems.com/Kyanite_Gems/Kyanite_gems_014.JPG

https://4.imimg.com/data4/AE/NE/MY-1909048/round-cut-blue-kyanite-stone-500x500.jpg

https://www.gemselect.com/photos/kyanite/kyanite-gem-474467a.jpg

I will continue adding to this essay my findings.