Here are some steps to remove rust stains from granite kitchen counters:

1. Identify the source of the rust stain and remove it if possible. For example, if it is caused by a metal object left on the counter, remove it and clean the area.

2. Mix baking soda and water to create a paste. The paste should be thick and not runny.

3. Apply the paste onto the rust stain and let it sit for 10-15 minutes.

4. Using a soft-bristled brush, gently scrub the paste onto the rust stain.

5. Rinse the area with water and dry it with a clean cloth.

6. If the stain still persists, mix vinegar and water in equal parts and apply it onto the stain.

7. Let the mixture sit for a few minutes and then scrub the area gently with a soft-bristled brush.

8. Rinse the area with water and dry it with a clean cloth.

9. Repeat the process if necessary.

Caution: Do not use any harsh chemicals or abrasive cleaners as they can damage the granite surface.