Amber is rumored to originate with the Adepti, but can now be found all over Liyue. This particular kind of amber used to possess the power to suppress evil. Prolonged exposure to the elements has carved it into the form it takes today: blades and spear-tips.
Where to Get Adeptus Amber: A Striking Sight?
This furnishing can be obtained from Realm Depot for 120 realm currency.