From Lost Fables Wiki
Topaz is generally a very clear, bright orange or yellow stone. It is fairly common and easy to find underground, making it less valuable for jewelry, while its true, and more valuable use is found in enchantments involving lightning.
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. Finally, emeralds are able to be used for an alchemist's focusing array.
When it isn't being used in mundane jewelry, topaz is useful for all sorts of enchantments involving lightning.
Weaponry and Armor
Weaponry imbued with topaz will typically electrocute those it strikes, while armor so imbued tends to make one resistant to shocks.
There are no topaz Artifacts on Anoma, perhaps you can change this.