Drilling a quartz countertop requires specialized tools and techniques. Here are the steps to follow:

1. Choose the right drill bits: Use diamond-tipped bits with a proper size and shape for your drilling needs.

2. Mark the drilling spot: Use a masking tape or a marker to indicate the spot where you want to drill.

3. Prepare the surface: Clean the area with a damp cloth and dry it well.

4. Secure the countertop: Use clamps or suction cups to hold the countertop securely in place while drilling.

5. Apply water: Apply a small amount of water on the drilling spot. This will prevent the quartz from overheating during the drilling process.

6. Start drilling: Start drilling slowly and steadily, using moderate pressure. Do not use too much force, as this can damage the countertop.

7. Remove debris: Stop drilling occasionally to remove the debris and cool the surface with water.

8. Finish drilling: Once you have drilled through the quartz countertop, remove the masking tape, and clean the area with a damp cloth.

Remember to wear protective glasses and gloves while drilling quartz countertops. If you are not comfortable doing it yourself, it is best to hire a professional to do it for you.