See with eyes
1. The back of the regular quartz stone will have the printing code of the stone company.
2. There should be lines on the back, because the hardness of the quartz stone is very hard, so there should be cut lines.
Soak in strong acid
3. Bubbles will appear around the inferior quartz stone after being soaked in strong acid.
4. This is a high-quality quartz stone, it will not bubble up after being soaked in strong acid.
Scrape with a knife
5. After the inferior quartz stone is scraped with a knife, the powder will appear.
6. The high-quality quartz stone is hard, there will be no powder after scraping, and the metal color of the knife will remain on the quartz stone.
Burn with fire
7. Add some detergent and water before scrubbing.
8. The high-quality quartz stone can basically be wiped clean after burning.