I'm sorry to hear about the issue with your brand-new marble countertops. If there is a natural-looking stain in one spot, there are potential ways to address it. While I can offer some general advice, it's essential to consult with a professional stone restoration expert for the best and safest approach, especially with brand-new countertops.
Here are some steps you can consider taking:
Identify the type of stain: Determine the nature of the stain before attempting any cleaning or repair. Marble can be sensitive to acidic substances like citrus juices, vinegar, or wine, which can etch the surface and create stains. Alternatively, organic stains (e.g., from food) or mineral stains (e.g., from water) may be present.
Test a small area: Before attempting any cleaning or repair on the entire countertop, perform a test on a small, inconspicuous spot to ensure the method won't cause further damage.
Use a poultice: For organic or mineral stains, you can try using a poultice to draw out the stain from the marble. A poultice is a paste made from a specific combination of solvents and absorbent materials. You can find commercial poultice kits for marble stains or consult with a professional to create a suitable one.
Seek professional help: For a new marble countertop, it's generally better to contact a professional stone restoration specialist or a marble care expert. They have the expertise and equipment to handle marble stains effectively without causing additional damage.
Prevent future stains: After addressing the current stain, take preventive measures to avoid future stains. Promptly clean up spills, avoid using acidic or abrasive cleaners, and ensure the countertop is appropriately sealed to minimize the risk of stains.
Remember, marble is a natural stone that requires specific care and maintenance. If the builder claims there's nothing that can be done, it's always a good idea to seek a second opinion from a reputable stone care professional who can assess the situation properly and offer suitable solutions.