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Yes, absolutely, if you want gems, get emeralds, they are geologically rare.
Even investment grade turquoise is better than diamonds.
Every extinct volcano has tons of diamonds in it.

Benitoite is a better investment. Extremely rare California state gem with a refractive index(fire) equal to or higher than diamond.

Benitoite

Good to know.

Don't let DeBeers see you spreading that truth around...!!!😎