As per title I am level 18 in mining and I still have yet to see a gemstone drop. I am playing in PVE Official America 2 server. The description is un-clear as to what percent chance they have to drop so I was unsure if this is bug or if they are just extremely rare.
Gemstones are incredibly rare. They have 1/1000 chance of dropping. So you might not ever see one.
But usually is you play consistently you can still find a few of them eventually.