But there is a practical way to tell whether it is pure silver or not.
Any sterling silver jewelry will be marked with "S925", indicating that the silver content is 925 per thousand. In the industry, 925 is pure silver.
If you don't feel at ease, there will also be a jewelry appraisal office near the jewelry store, so you can go for re-inspection.
I hope my answer can help you! Please feel free to ask me if you have any other questions.