About Diamond Concrete Supply

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Diamond Concrete Supply, Inc. was founded in June 1979 by Mervin Brandt, establishing a company built on hard work, reliability, and quality service

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In 2000, Guillermo Dupleich acquired the company and began a new era of growth and transformation. Under his leadership, Diamond Concrete transitioned from volumetric trucks to traditional ready-mix concrete mixer trucks and later expanded operations with the purchase of a concrete batch plant — significantly increasing production capacity and market reach.

Over the years, Guillermo led major projects, including work at the U.S.–Mexico border and contracts with the City of San Diego. His dedication to excellence and strong work ethic helped establish Diamond Concrete as a trusted name throughout the region.

Guillermo’s daughters worked alongside him, playing a vital role in the company’s continued growth and management. Although now retired, Guillermo remains involved as a mentor.

Today, Jennifer Magarro serves as President of Diamond Concrete Supply. Having worked alongside her father since 2000, Jennifer is committed to honoring his legacy while leading the company into its next chapter — preserving the values, integrity, and vision that have defined Diamond Concrete for decades.