Quartz and diamond are two of the most common minerals on Earth. While they share some similarities, there are also some key differences. Here are a few ways to test quartz from diamond:

1. Hardness. Quartz is a 7 on the Mohs scale of hardness, while diamond is a 10. This means that diamond can scratch quartz, but quartz cannot scratch diamond.

2. Cleavage. Quartz has a conchoidal fracture, which means that it breaks into curved, shell-like pieces. Diamond has a cubic cleavage, which means that it breaks into flat, even pieces.

3. Luster. Quartz has a vitreous luster, which means that it shines like glass. Diamond has an adamantine luster, which is a bright, sparkling shine.

4. Specific gravity. Quartz has a specific gravity of 2.65, while diamond has a specific gravity of 3.52. This means that quartz is less dense than diamond.

5. Conductivity. Quartz is a poor conductor of electricity, while diamond is a good conductor of electricity.

6. Refractive index. Quartz has a refractive index of 1.544, while diamond has a refractive index of 2.417. This means that diamond bends light more than quartz does.

By using these tests, you can easily identify quartz from diamond.