Our Certification


The company must apply to begin the rating process.


A random sample of typically 400 past customers is collected from all customer files of the applicant company.


Only real customers are surveyed in confidential telephone research to determine the company’s customer satisfaction score based on quality.


To qualify, the company must score Highest in Quality and Helpful Expertise®, with a score of 90 or above on a 100 scale.


We confirm that the company has required insurances and valid state-mandated credentials.


The company must perform to contract, have customer-friendly business practices and stand behind its work.


The company agrees to adhere to the Diamond Certified® Customer Satisfaction Principles.


If the company’s quality rating, business practices and credentials meet our high standards, it is awarded Diamond Certified.


We conduct ongoing surveys to ensure the company is maintaining high customer satisfaction and loyalty.


The company agrees to participate in Diamond Certified mediation if necessary.


The Diamond Certified Performance Guarantee provides added assurance of the company’s commitment to customer satisfaction.


Companies that are able to qualify for and maintain their Diamond Certified awards are much more likely to deliver quality to their customers.

Only companies rated Highest in Quality and Helpful Expertise® earn Diamond Certified.
Review websites can be helpful, but you have to be careful when using them. It’s important to understand the key differences between how the Diamond Certified Resource (DCR) conducts research and how review sites collect reviews. While DCR exclusively conducts telephone surveys from an entire customer base of each rated company, review sites post reviews from any person who chooses to post, which means legitimate, spontaneous reviews are mixed with fake and cherry-picked reviews that come from a company’s best customers, family and friends. Due to the accuracy of its ratings, DCR is able to back your purchases from top rated companies with the Diamond Certified Performance Guarantee, while review sites do not. For these reasons, consumers are naturally encouraged to first look to top rated Diamond Certified companies whenever possible.
Diamond Certified Resource (DCR)
Most Review Sites
Real Customers

To start each rating, DCR uses a company’s actual customer list. The DCR only performs its surveys by telephone, which allows it to verify that each customer has actually purchased from the company being rated.

Fake Reviews / Multiple Identities

Anyone can post an anonymous review, whether they were a customer or not. Roughly 30% of posted reviews are fake. Anyone can game the system by creating multiple identities and posting fake reviews to bolster bad companies, or sabotage good ones.

Random Sample / All Customers

DCR receives all customer names and phone numbers or a large, random sample of customers (400) from each rated company. Company owners can’t cherry-pick because of such a large base. Thus, dissatisfied and satisfied customers are surveyed in true proportion to their occurrence.


Review sites encourage companies to ask people to write reviews. Many times, owners and employees solicit their families, friends and best customers to post 5-star reviews. This cherry-picking produces misleading and biased results.

Statistically Reliable / Rigorous

DCR research is statistically reliable because a large, random sample of customers is pulled from each company’s customer base. Customers are “interrupted” by phone interviews at home, so there’s not a self-selection bias. Ongoing research, complaint and credentials ratings ensure Diamond Certified companies continue to perform well.

Inaccurate Star Scores

Each company’s “star score” (calculated by averaging scored reviews) isn’t an accurate score for customer satisfaction because review posters aren’t derived from a random sample that represents all customers served. Instead, customers and non- customers are solicited to write reviews.

Performance Guarantee

The Diamond Certified Performance Guarantee provides mediation and a money-back guarantee (up to $1,000) if a customer has a problem with a Diamond Certified company.

No Guarantees

Most sites don’t offer a performance guarantee.

Performance Guarantee

A dispute may arise from an unmet expectation or a simple misunderstanding. Many disagreements are resolved after the parties work with each other using the contract and industry standards for guidance.

If you have tried unsuccessfully to resolve a disagreement please contact us at [email protected] or (800) 738-1138. Our mediator will work with you and the Diamond Certified® company to attempt to reach an agreement that both parties can live with.

If the mediation fails to produce a mutually-agreeable solution due to failure of the Diamond Certified company to honor contractual obligations, uphold industry standards, or participate in good faith, we will refund your purchase price up to $1,000.

To qualify for this guarantee, you must:

  • Have purchased the services of a company that was Diamond Certified at the time of the transaction
  • Have attempted to resolve the issue with the company directly
  • Bring the matter to our attention within 6 months of the qualified purchase
  • Have no previous or concurrent complaints against the subject company elsewhere
  • Be willing to allow the company to correct the problem

What does a company have to do to earn Diamond Certified®?

Each company must undergo a rigorous rating process and earn a customer satisfaction rating of 90 or higher (on a 100 scale). Companies that score Highest in Quality and Helpful Expertise® in customer satisfaction, insurance coverage, license, business practices and complaint bureau status earn Diamond Certified. Most companies can’t make the grade.

What questions are asked to determine a service provider’s customer satisfaction rating?

The following questions are asked:

1. On a scale of 1 to 10, with 1 being very dissatisfied and 10 being very satisfied, how do you feel about the quality you most recently received from (name of company)?
2. If you needed these services in the future, would you use (name of company) again?
3. If you needed any helpful expertise, did (name of company) provide that expertise?
4. When you think about (name of company), what would you like to tell other consumers?
5. What did you like best about (name of company)?
6. What do you think (name of company) could do to improve?

Why do you say your ratings are more accurate than review sites?

Unfortunately, many online review sites are plagued with fake and cherry-picked reviews, where anonymous posters pretend to be customers and reviewed companies solicit their favorite customers to post reviews. Conversely, our ratings are based on statistically reliable research that’s derived from a large, random sample of each company’s verified customer base. We conduct telephone surveys to ensure we survey only real customers of the company being rated, and we require every Diamond Certified company to pass ongoing research and credential ratings in order to maintain their certification.

What if I have a problem with a Diamond Certified company?

Contact the senior manager of the company and explain the problem. Use the original service contract for reference. Describe what reasonable measures the company can take to correct the problem. If the issue remains unresolved, please review the terms of the Diamond Certified Performance Guarantee and contact us at (800) 738-1138.

Can a company cheat to earn Diamond Certified?

It’s possible, but highly unlikely. A company with low customer satisfaction has a problem hiding that fact because most customers don’t bother complaining. We survey a large, random sample of past customers, conduct ongoing research and monitor all complaints received. Companies that fail to keep their customers satisfied are disqualified.

Why don’t you tell us which companies don’t pass your rating and certification?

All companies are guaranteed anonymity in the rating process so they’re more likely to apply to be rated. To be safe, use a Diamond Certified company.

Why do you limit the number of companies that can earn Diamond Certified?

Only companies rated Highest in Quality and Helpful Expertise® earn Diamond Certified. In addition, we limit the number of companies participating by industry, so while there are enough companies displayed to provide you with choice, the limited number allows us to closely monitor these companies to ensure your satisfaction.

Who pays for the rating? How does American Ratings Corporation generate money to cover costs?

Companies that go through the rating process pay a rating fee and receive a pass or fail research report. Companies that qualify and earn Diamond Certified pay an annual certification fee, allowing us to monitor the Diamond Certified brand, conduct each company’s ongoing customer satisfaction research, provide mediation, back you with the Diamond Certified Performance Guarantee, and educate the public.

Do you conduct criminal background checks?

The rating steps that we conduct are described in the previous FAQs. We do not conduct criminal background checks. So, if this is important to you, when choosing your next service provider, do not hesitate to ask the company representative whether the employees who will be working in your home have passed criminal background checks and what additional measures will be undertaken to protect your family and your property while work is in process. If you have children, you may also want to check out the Megan’s Law website at www.meganslaw.com. Information is power. It is our hope that this information has provided an added measure of decision-making power in your hands.

  • Customer Partnership

    • “I always want to make sure I’m dealing with a business that’s professional, and American Canyon Collision Center did honest, straightforward work.” -Lasonja Zeigler

    • American Canyon Collision Center's staff is committed to quality in every aspect of their work.

    You will feel confident in the relationship

    Like the Yin and Yang symbol, this image depicts the principle of perfectly balanced forces. One side is the customer desiring the highest quality. The other side is the Diamond Certified company prepared to deliver on all its promises. Together, they partner to produce a mutually beneficial performance.

  • Highest Quality

    • “Seeing the Diamond Certified symbol on Dr. Jag Dhesi’s website made me more confident to call and make an appointment. He was great and it reassured me that I made the right choice.” -Rosanna Papageorge

    • Dr. Jag Dhesi and his staff at Springtown Wellness Center believe in giving each patient the same respect and quality care that they would give to their own families.

    You will see the results

    For thousands of years, the diamond has symbolized the highest achievement of quality. Thus, Diamond Certified is only earned by companies consistently scoring Highest in Quality and Helpful Expertise® in ongoing customer satisfaction research.

  • Trust

    • “I put more trust in selecting a company from the Diamond Certified Directory. I found HOUSEworks and I’m very happy with their entire team. They did a complete remodel on my home and it looks fantastic.” -Tami Aviles

    • “Remodeling is a deeply personal process—we’re inside our clients’ homes and they have specific ideas about how they want things to look, and the only way to make that happen is to listen.” -Jeff Kann, owner of HOUSEworks

    You will take comfort in a job well-done

    Diamond Certified companies have an obligation to deliver on their promises to consumers. Each of your transactions is backed by the powerful Diamond Certified Performance Guarantee.

  • Satisfaction

    • “I was completely satisfied with DC Tile and Stone’s work. They did some travertine work for me and they did a great job.” -Marc Meyer

    • “We strive for 100 percent customer satisfaction, so we never leave a job until the homeowner is completely happy with our work.” -Derek Kahn, CEO of DC Tile and Stone

    You will be impressed with the achievement

    Only you know if you’re satisfied. This striking image of beauty and personal fulfillment represents your ideal assessment of the Diamond Certified company’s performance.

  • Pride

    • “Los Gatos Roofing was different than any other roofing company I’ve dealt with. They were really passionate about their work and I could tell I was dealing with a quality company.” -Mo Hamani

    • Cameron Radonich, Los Gatos Roofing's marketing director, says the company is committed to offering the highest quality craftsmanship available.

    You will sense the commitment

    Pride is a powerful human motivation. Professionals who work at Diamond Certified companies are passionate about performing their best.