Diamond Certified Resource Welcomes Four New Top Rated Companies in October 2026

Based on a large survey of only verified customers, only companies rated Highest in Quality and Helpful Expertise^® earn Diamond Certified.

PETALUMA, Calif., Oct. 30, 2026 /PRNewswire/ -- Diamond Certified Resource has announced that four companies earned the prestigious Diamond Certified award in October 2026 by scoring Highest in Quality and Helpful Expertise : Cordoza Electric, MaksBuilder, Professional Plumbing Inc. and Radvand Construction.

The Diamond Certified Research Team's methodology ensures only a large, random sample of verified customers are surveyed, which produces the most accurate ratings of local companies available. The team conducts a 12-step rating and certification process that identifies companies delivering high quality and Helpful Expertise to their customers. The process includes collection of a large, random sample of customers; confidential telephone and email surveys of real customers; and verifications of state licenses, insurance, and business practices.

The research team produces a final Diamond Certified Research and Ratings Report. Only companies that score 90 or above on a 100 scale are rated Highest in Quality and Helpful Expertise and earn Diamond Certified. If a company falls short of these standards, it does not earn Diamond Certified, regardless of how much it's willing to pay. Qualified companies agree to follow the Diamond Certified Customer Satisfaction Principles and participate in mediation if needed, and they're backed by the Diamond Certified Performance Guarantee. Ongoing surveys and monitoring help ensure continued high customer satisfaction by Diamond Certified companies.

"Earning Diamond Certified is a significant achievement because most companies can't qualify," says Greg Louie, founder and CEO of American Ratings Corporation, creator of Diamond Certified Resource. "These four companies have demonstrated the quality, Helpful Expertise and customer commitment required to earn the award."

Every Diamond Certified Research and Ratings Report includes detailed statistical results (such as average satisfaction scores and response distributions), verbatim customer survey responses and visual charts that clearly present the findings. "Our Report shows each customer's rating on a 1 - 10 scale of the company's quality, whether they would hire the company again, if the company provided Helpful Expertise and verbatim answers to open-ended survey questions, which adds context to our research-grade report," says David Pak, Director of Ratings at American Ratings Corporation.

Here's more information about the four companies that earned Diamond Certified in October 2026:

Cordoza Electric
Cordoza Electric provides electrical installation, maintenance, and repair services for residential and commercial clients in Solano, Yolo, Sacramento, Napa, Contra Costa, Marin, and Sonoma Counties. The company has the training and equipment to take on projects of every size, from basic panel upgrades to complete home rewires, and it also installs lighting systems in various interior and exterior applications.

MaksBuilder
MaksBuilder offers a wide range of HVAC services to residential and commercial clients throughout Orange County. The company has the in-house capabilities to install, repair, and maintain everything from central heating and cooling systems to specialized products like ductless mini-splits and high efficiency heat pumps, and it also offers 24-hour emergency service during the work week.

Professional Plumbing Inc.
Professional Plumbing Inc. provides a wide range of plumbing services for residential and commercial clients throughout Orange County. The veteran-owned and family-run company is qualified to handle everything from routine fixture repairs and water heater installations to gas line maintenance and slab leak repairs, and it also offers 24/7 emergency service for the convenience of its customers.

Radvand Construction
Radvand Construction remodels kitchens and bathrooms; builds room additions and accessory dwelling units (ADUs); and provides various new construction services for homeowners in Santa Clara and San Mateo Counties. As a design/build firm, the family-owned and operated company is qualified to handle each step of the remodeling process in-house.

It's easy to find top rated companies in the San Francisco Bay Area and Other Areas on Diamond Certified Resource.

Alameda County
Contra Costa County
El Dorado County
Fresno County
Los Angeles County
Marin County
Milwaukee County
Monterey County
Napa County
Orange County
Placer County
Sacramento County
San Benito County
San Francisco
San Joaquin County
San Mateo County
Santa Clara County
Santa Cruz County
Solano County
Sonoma County
Yolo County
Yuba County

About American Ratings Corporation
American Ratings Corporation (ARC), the creator of Diamond Certified Resource, the source for consumers who love quality local companies, rates local companies by surveying only their verified real customers to produce the country's most accurate ratings of local companies. It also creates deeply researched company reports and consumer guides that give consumers the best companies plus the best advice for choosing a local Auto, Home, Health or Personal service type of company.

Only companies rated Highest in Quality and Helpful Expertise^® earn Diamond Certified and are backed by their Performance Guarantee. All their deeply researched reports and guides are available for free at diamondcertified.org. They also produce an annual, full-color, printed Diamond Certified Directory with 840,000 copies published in 9 geographic zones in the Greater San Francisco Bay Area. Each April, these are mailed for free to their 182,000 Diamond Certified Preferred Members and selected homeowners and companies.

SOURCE American Ratings Corporation