De Koch (non-capitalized: de Koch; also deKoch) is a jeweller from Grand Theft Auto: San Andreas, Grand Theft Auto IV and Grand Theft Auto: Chinatown Wars that specialises in diamonds. The brand is advertised on the radio and on billboards in Grand Theft Auto: San Andreas but it is not found in San Andreas as a business, although the business address on the billboards read Dix Road, Los Santos. Their slogan is "Shut that bitch up with ice". In Grand Theft Auto IV, de Koch has several shops, especially around Algonquin. The company is a parody of De Beers.
- The name is a play on the phrase the cock.