Hello, so, I came back here after 1 year and I saw your messages. Why isn't this a bug though? Is it because coding gem trees to be mined with pickaxes would cause unexpected issues due to them being classified as regular trees in the game code?
Also, about what whoneedsnamestbh said, this is because ALL solid blocks and decorations, with no exceptions, are mined with a pickaxe. This is not something that applies only to wood and blocks obtained from plants that you can chop-down with an axe. I pointed out bamboo being mineable with a pickaxe because it's wood-based and also a tree, so the most logical thing would be it being mined with an axe instead. However, the gemstone trees being mined with a pickaxe instead is way more nonsense, becase if we need to mine bamboo with a pickaxe, why don't we need to do the same with gem stone trees? I mean, they are made of stone!