We can't judge the authenticity of amethyst original stone by whether there are traces left after the knife is scratched. Amethyst is so hard that it really won't leave any marks when scratched with a knife. However, if a piece of amethyst is dyed or synthesized, it may leave traces after being cut with a knife. Therefore, more methods are needed to identify the authenticity of amethyst, such as observing its color, transparency and crystal morphology.

The above information is for reference only. If you have any questions about Crystal, please consult a professional for more information.