From Lost Fables Wiki
Amethysts are a fairly common stone, being found in relatively large quantities inside of geodes. Because of how common they are, they are not especially prized by people seeking to make them into jewelry, and the enchantments they carry are only moderately useful.
Generally speaking, when a gem is used for enchantments, it is either embedded into the metal of the weapon while it cools, or crushed into a fine powder and incorporated into the metal itself as it is forged.
Amethyst is almost always used in enchantments for increasing the weight of an object. They can also be used in enchantments for the reverse effect, but doing such is more difficult and costly, and thus most simply opt to use lighter materials where possible.
Weaponry and Armor
Through amethyst enchantments, critical parts of weapons and armor can have their weight changed, making them significantly easier to carry, or significantly more effective in combat. The most advanced enchantments with amethyst cause weaponry to only gain weight once it is being swung, to minimize the fatigue generated.
There are no amethyst Artifacts on Anoma, perhaps you can change this.