The Certification Process






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  • Accurate Ratings

    Local companies rated
    Highest in Quality and Helpful Expertise™

  • Performance Guaranteed

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    Backed by Mediation

  • Deep Info™

    Researched company reports.
    Essential articles and videos by topic experts.


Barbara Schallau Consumer
Bay Area

Hany Louis CEO/General Manager
The Tile & Grout King Inc.

Jagdish Hegde Consumer

Leigh Bakhtiari President
City Carpets

Cecile Monfort Consumer
San Jose

Mark Corrallo President
All Seasons Construction

Jim Baylor Consumer
Bay Area

Bev Oliver Consumer
Bay Area

Gifford Teeple Owner
A Reliable Handyman

Tami Aviles Consumer
Bay Area

Tommy Herren Owner
The Lighting Geek

Watch this video on the Diamond Certified Resource: the most accurate and trustworthy way to find local companies rated Highest in Quality and Helpful Expertise.

We’ve all felt the joy of choosing a good local company and, unfortunately, the pain when we mistakenly choose a bad one. The problem is, every company claims to be good, yet despite these glowing claims some provide inconsistent quality while others are downright unscrupulous.

We’ve solved this problem for you with the Diamond Certified Resource. Only local companies independently rated Highest in Quality and Helpful Expertise™ earn Diamond Certified. Our rigorous rating and certification process starts with the in-depth pass/fail rating of each company’s customer satisfaction, license and insurances. Most companies can’t pass our rating and earn Diamond Certified, and every Diamond Certified company must continue to deliver on its promises to you, the consumer. That’s why we conduct ongoing customer satisfaction research and credential-based ratings and monitor each company’s performance.

Every Diamond Certified company is backed by our powerful Performance Guarantee, so you’ll feel confident in your choice when you use our always-free web resource or Diamond Certified Directory. If you try unsuccessfully to resolve a disagreement with a Diamond Certified company, our mediator will work with you and the 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.

Each time you visit, you’ll see each Diamond Certified company’s Deep Info, including researched company rating reports, verbatim survey responses, essential articles, photo galleries, videos and expert tips. We put all the information you need to choose a company in one place, and no other web page can match this depth of information.

When you choose a Diamond Certified company, you’ll never be fooled by fake or cherry-picked reviews because we survey a large, random sample of each company’s customers by telephone (typically 100 surveys) to get the most accurate ratings and verify only real customers are responding. Company owners can’t cherry-pick by telling friends and selected customers to post 5-star reviews on our site—we don’t allow it.

So, if you want quality, you’ll have confidence in choosing a Diamond Certified company. We encourage you to visit this website on a regular basis to find updated ratings on top rated companies in your area, see verbatim survey responses on each Diamond Certified company, and read thousands of industry-specific expert articles and tips. We care about customer satisfaction, and we care about you. We’re proud to give you all the information you need to choose with confidence.



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Each Diamond Certified Company Report gives you the most accurate and comprehensive Deep Info available for each company. It includes proof of Diamond Certified status, rating charts, verbatim survey responses, essential articles about the company, a capabilities table, a Diamond Certified Video Profile, key photos, company owner expert tip contributions and more. Click on the graphic to learn more


    We survey a large, random sample of each company’s customers by telephone to get the most accurate ratings...


    In addition to providing rating scores for Quality, Intent to Return and Helpful Expertise, each surveyed customer is...


    You get to see the company in action, meet the managers, and learn as they describe their specialties and customer...


    You can choose to scan or go deep into these five researched articles on each Diamond Certified company: Company...


    Each company’s key info is logically organized within this table. You’ll find this system of display gives...


    Top rated local company owners are experts in their fields, and they’ve written topic-based expert articles and created...


    If a picture is worth a thousand words, how about an entire portfolio? You’ll get a better sense of each company once...


    This is a good place to go if you want to do extra research on a company. Here you’ll find a link to each company’s...

Video: Three Ways to Downsize Your Belongings

Posted on July 19, 2018 by James Florence

Earlier this week, we posted an article featuring expert tips on preparing for a move. One recommendation was downsizing your belongings to avoid a steep moving bill. To learn more about the downsizing process, watch this informative video by Mario Batz, general manager of Johnson & Daly Moving & Storage in San Rafael.


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Posted in: Moving, Diamond Certified Experts

How Cool is Your Roof?

Posted on July 12, 2018 by James Florence

Everybody wants to be cool, and in more ways than one. Besides sporting stylish clothes and a laid-back attitude, we all want to maintain a comfortable body temperature. However, just as it’s tough to look cool in outdated attire, it’s difficult to stay cool when you have an outdated roof, especially during summer. The question is, how cool is your roof? Read more

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Posted in: Roofing, Energy Efficiency

How to Be Their Favorite Customer

Posted on July 10, 2018 by Jennifer Chan

Today, we’re revisiting a subject important to anyone embarking on a home improvement project: how you can help streamline the process by being a good customer. Below, Greg Louie, CEO of American Ratings Corporation, discusses what you can do to help foster the success of any project.

How to Be Their Favorite Customer
When you work with a local company, it’s ultimately their responsibility to perform a thorough and complete job, but you play a big part in the success of your project, too. Here are a few simple steps you can take to be their favorite customer:

  • Be clear and upfront with the company representative.
  • Outline the problem,
  • Read more

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Posted in: Consumers, Home Improvement
Tags: , ,

  • Regan R.

    Verified customer
    Quality 10
    Loyalty Yes
    Helpful expertise Yes

    This year I've been through four contractors, and he's the only one I would hire back. He saved me.
    I had four contractors before him who messed me up in various ways, but he saved me. He has no ego. He's not just a good contactor, he tries to be as fast as can, but he never compromises quality. He's honest, and he answers the phone. Because of him, I'm thinking of buying a piece of land and having him build me a house from scratch, not a remodel. His finish work is impeccable. I just keep calling him back for jobs because I know he can do the work.

    Response to Diamond Certified Company California Dreaming Construction

  • Rachel R.

    Verified customer
    Quality 10
    Loyalty Yes
    Helpful expertise Yes

    I would recommend them.
    They were prompt, they always took my calls, appointments were fairly quick to schedule, and all the people I dealt with were nice, both on the phone and the techs that came out to the house. I've had them do plumbing, and also gas lines, they do really good work on both of those, I was really satisfied.

    Response to Diamond Certified Company Rayne Plumbing and Sewer Service, Inc.


Ilan Sigura is a lifetime veteran of the construction industry and CEO of Sigura Construction, Inc. a Diamond Certified company since 2007. He can be reached at (408) 372-8945 or by email.


Ilan Sigura: An Integral Career

By James Florence, Diamond Certified Resource Reporter

SANTA CLARA — By the time he reached early adulthood, Ilan Sigura had already established deep roots in the construction industry. Even when he tried his hand at a new profession, it wasn’t long before he returned to the field that had become an integral part of his identity. “My father was a contractor, and he began teaching me the trade when I was just a boy,” he explains. “Later, as a college student, I decided to study computer science. After I graduated, I spent a couple of months engineering software for a tech company, but I didn’t like it at all. Read more

Expert tip
Crucial Aspects of Green Building
SANTA CLARA – When it comes to designing and executing a remodeling project, one of the most important considerations is energy conservation. Building codes require a certain level of energy efficiency, but there are many opportunities to go above and… Read more

Graham Jones is owner of The Genteel Plumbers, a Diamond Certified company. He can be reached at (650) 525-4193 or by email.


Graham Jones: A Unexpected Direction

By James Florence, Diamond Certified Resource Reporter

SAN FRANCISCO — Graham Jones never planned on becoming a plumber, but when his original professional pathway diverged, that’s the direction it took him in. “I was actually going to automotive school, with plans to become a mechanic,” he recounts. “However, at a certain point I realized it wasn’t the right career for me, mostly because I didn’t want to be stuck in the same place every day. I expressed this to my brother, who’d recently switched from working as a chef to becoming a plumber. He recommended I look into plumbing, so I did. I ended up doing an apprenticeship with a company in San Rafael, Read more

Expert tip
An Easy Way to Maintain Your Sink Drains
SAN FRANCISCO — To prevent clogged sink drains, it’s a good idea to routinely clean out your drain pipes. Rather than using a store-bought drain cleaner like Drano®, try a simpler method: dish soap. It’s no wonder that dish soap… Read more

Dr. William Hummer is owner of William R. Hummer, DDS, a Diamond Certified practice since 2002. He can be reached at (510) 351-5711 or by email.


Dr. William Hummer: An Early Calling

By James Florence, Diamond Certified Resource Reporter

SAN LEANDRO — Many people find their professional callings in adulthood, but Dr. William Hummer knew much earlier what he wanted to do with his life. “I was 13 years old when I decided I wanted to be a dentist,” he affirms. “Around that time, a lot of my peers were talking about what they wanted to do when they grew up. I had just gotten braces, so I naturally thought of my orthodontist. He had his own business, made his own schedule and earned a nice income; plus, he got to work with his hands and take care of people for a living. Read more

Expert tip
Heeding the Warning Signs of Oral Cancer
SAN LEANDRO — Treating cancer is one of the great challenges of modern health care, and dentistry is no exception. According to the Oral Cancer Foundation, nearly 50,000 people in the United States are diagnosed with oral cancer each year,… Read more

Brandon Stieg is president of Pacific Circle, Inc., a Diamond Certified company since 2007. He can be reached at (415) 785-8044 or by email.


Brandon Stieg: Finding a Balance

By James Florence, Diamond Certified Resource Reporter

LAGUNITAS — As a young man, Brandon Stieg had a talent for architecture, but he preferred being outside to sitting at a drafting desk. Eventually, he was able to find a balance between the two. “I’ve always been artistic, but I was also good at math, so when I got to college, it made sense to major in architecture,” he recounts. “However, soon after starting an architectural apprenticeship, I realized I didn’t want to be an architect. The idea of being at a desk for eight hours a day just didn’t appeal to me—I wanted to be working outside. Read more

Expert tip
Metal Enhancements for Wood Decks and Fences
LAGUNITAS — Natural wood is a popular material for building exterior structures like decks and fences. However, due to wood’s sensitivity to the elements, these types of structures are often prone to functionality and maintenance issues. A good way to… Read more

Jay Kats is owner of Revolt Electric, a Diamond Certified company. He can be reached at (408) 412-9754 or by email.


Jay Kats: All Revved Up

By James Florence, Diamond Certified Resource Reporter

SUNNYVALE — For Jay Kats, a love of cars ultimately led to a career as an electrician. “I’ve been working on cars since before I was old enough to drive,” he affirms. “In the course of learning mechanical work, I also learned how to work with the electrical aspects of automotive. However, when it came time to get a job, I didn’t want to be a mechanic, mainly because I didn’t like being stuck in one place, even if it was a garage. Since I was well-versed in automotive electrical, I decided I would learn to do electrical work on a wider scale and become a professional electrician.”

Today, Read more

Expert tip
How to Identify Unsafe Circuit Breakers
SUNNYVALE — Like most inconspicuous household components, residential electrical panels are often overlooked, which is why many Bay Area homes still have their original circuit breakers. The problem is that some old circuit breakers pose significant safety hazards. Two examples… Read more

Cori Chipman is chief operations officer of No More Dirt, Inc., a Diamond Certified company. She can be reached at (415) 484-5907 or by email.


Cori Chipman: A Dynamic Career

By James Florence, Diamond Certified Resource Reporter

SAN FRANCISCO — Cori Chipman never planned on getting a job in the janitorial industry, but after nearly a decade, she’s glad she did. “I doubt that I would have applied at a janitorial company if it weren’t for the 2008 recession,” she explains. “I was working in the hospitality industry in Hawaii and the recession hit us particularly hard. I ended up moving back to San Francisco, where I immediately began looking for work. One of the companies I applied at was No More Dirt. I had no idea what working for a janitorial company would be like, Read more

Expert tip
Strategy for Maintaining a Breakroom Refrigerator
SAN FRANCISCO — A janitorial hot spot in most offices and workplaces is the breakroom refrigerator. When this gets neglected (which is commonly the case), it can result in foul odors, mold growth and other unpleasant developments. One day, it’s… Read more

Dr. Lei Luo is president of Lei Luo, D.D.S. Family & Implant Dentistry, a Diamond Certified practice. He can be reached at (650) 525-4186 or by email.


Dr. Lei Luo: Dental Migration

By James Florence, Diamond Certified Resource Reporter

SAN BRUNO — When Dr. Lei Luo came to the United States to learn about new techniques in dentistry, he hadn’t planned on becoming a permanent resident, but that’s exactly what happened. “I began my dentistry career in China in the early 1980s,” he recounts. “I originally got into dentistry on the advice of my father, who was a doctor. He thought it would be a good profession for me to pursue, especially since dentists were in high demand. In 1996, after practicing for more than a decade, I wanted to increase my skills and knowledge, so I came to the U.S. Read more

Expert tip
Dental Implant Advantages
SAN BRUNO — When it comes to replacing missing teeth, the most popular method in use today is dental implants. Essentially, a dental implant is an artificial tooth fastened onto a metal post that’s surgically implanted into the patient’s jawbone.… Read more

Rod Tehrani is owner of Absolute Plumbing and Drain, a Diamond Certified company. He can be reached at (925) 267-8561 or by email.


Rod Tehrani: A Technical Advancement

By James Florence, Diamond Certified Resource Reporter

CONCORD — After eight years of working construction, Rod Tehrani felt it was time to advance to something a little more technical. “I decided to look into plumbing,” he relates. “At first, it was a lot more grunt work than technical, but that changed with time. The more I learned about the intricate aspects of the profession, the more I enjoyed it. Eventually, I got hired by the county as a crew leader for underground pipe replacement projects. In 2002, I started my own plumbing business, and it has been growing ever since.”

Today, as owner of Absolute Plumbing and Drain, Read more

Expert tip
The Advantages of an Earthquake Safety Valve
CONCORD — Due to high levels of seismic activity, earthquake safety is no small matter in the Bay Area. If you’re a homeowner, this means ensuring your home is structurally reinforced with supplementary measures like bolting and bracing. It’s also… Read more

Chris Street is a longtime veteran of the HVAC industry and president of Enviro Heating & Air Conditioning, Inc., a Diamond Certified company since 2014. He can be reached at (707) 809-5969 or by email.


Chris Street: A Second Trade

By James Florence

ROHNERT PARK — When a debilitating injury ended his roofing career, Chris Street found himself starting from scratch in a new professional field. In the end, however, his twist of fate resulted in a greater success than he’d ever imagined. “I developed carpal tunnel syndrome early in my roofing career, and when I had surgery to correct it, I lost about 20 percent usage of my wrists,” he explains. “Since I wasn’t able to do roofing anymore, the workers’ compensation department offered to send me to school to learn a new trade. I decided to go into HVAC—I used to see HVAC technicians doing installations on the sites I worked at, Read more

Expert tip
Preventative HVAC Maintenance
A little preventative maintenance can go a long way toward keeping your home’s heating and cooling system performing optimally. The best way to ensure this is by having a professional HVAC technician perform an annual maintenance service on… Read more

Tatiana Acevedo is an account manager at No More Dirt, Inc., a Diamond Certified company. She can be reached at (415) 484-5907 or by email.


Tatiana Acevedo: A Clean Transition

By James Florence, Diamond Certified Resource Reporter

SAN FRANCISCO — Tatiana Acevedo already had plenty of management experience when she came to California from her home country of Puerto Rico, so when she landed a management job with a janitorial service, it was a clean transition. “Prior to moving to California, I worked for a paint and construction product manufacturing company, where I managed accounts with major retailers like Home Depot and Walmart,” she explains. “A few years ago, my husband got a job offer in California, so we uprooted from our home in Puerto Rico and came to the Bay Area. After transitioning to my new life, Read more

Expert tip
Janitorial Tips for Tenancy Transitions
SAN FRANCISCO — Running an HOA or a common workspace can be challenging, especially when it comes to tenant turnover. After all, there are many details to address in the interim between tenancies, and how you handle this transition can… Read more

Dain Vogel is an account manager at No More Dirt, Inc., a Diamond Certified company. He can be reached at (415) 484-5907 or by email.


Dain Vogel: A Clean Opportunity

By James Florence, Diamond Certified Resource Reporter

SAN FRANCISCO — Any employee likes having a good boss, but Dain Vogel really lucked out when he got a chance to work for his longtime mentor. “After six years working as an elementary school teacher, I was looking for a career change,” he recounts. “About that time, I came upon a job opportunity with No More Dirt. I’ve known the owner, Nick Mettler, for a long time. Nick has always been a bit of a mentor to me—I’ve often gone to him for advice and he has helped guide me along my path. So, naturally, when I got a chance to work for him, Read more

Expert tip
The Importance of Dispenser Keys in Commercial Spaces
SAN FRANCISCO — If you’re a business owner moving into a new commercial space, the first thing you’ll likely ask for is a key to the front door. However, there’s another type of key that’s important in commercial properties yet… Read more

Ryan Cordes is manager of European Sales & Service, a Diamond Certified company. He can be reached at (707) 836-3960 or by email.


Ryan Cordes: Earning His Birthright

By James Florence, Diamond Certified Resource Reporter

SANTA ROSA — When Ryan Cordes started working at his father’s auto repair shop, he wasn’t given any special privileges—he had to work his way up from the bottom like everyone else. “I began working for my dad in 2000, right after graduating from high school,” he recounts. “I started out mopping floors, moved up to washing cars, spent some time in the parts department and was eventually promoted to shop manager in 2011. All along the way, I entertained different ideas for what career I wanted to go into, but ultimately I decided to stay put. I enjoy working on cars and interacting with customers, Read more

Expert tip
Caution for Buying a Used Mercedes-Benz
SANTA ROSA — If you’re interested in buying a used Mercedes-Benz, there’s something you should be aware of. Certain models from 2004 to 2008 are known to have a problem with their timing chains, caused by a defective balance shaft.… Read more