George F. Labram worked as a mining and mechanical engineer at various places in the United States and also designed and sold machinery for a firm in Chicago. In 1894 he came to South Africa to supervise the erection of a washing plant for De Beers Consolidated Diamond Mines at Kimberley. He stayed with the firm and was appointed its chief mechanical engineer in October 1896. With F.B. Kirsten he invented the grease-table method for automatically sorting diamonds, which was patented by Kirsten in 1897. De Beers bought the rights to the process from Kirsten and Labram's estate in July 1900. In 1899 he was granted a United States patent for an improved braking system for trucks and other vehicles. In 1898 and again in 1900 he was appointed as an examiner in engineering for mining students of the University of the Cape of Good Hope.
When Kimberley was besieged by Boer forces at the outbreak of the Anglo-Boer War in October 1899 Labram helped to fortify the town. Among others he designed and constructed a plant for the bulk refrigeration of perishable foodstuffs and installed an emergency fresh-water supply system. He also gained the support of Cecil J. Rhodes, the chairman of De Beers, to build a field gun for the town's defence and this he did with the help of Edward Goffe*, the chief draughtsman at De Beers. The barrel of their massive 104 mm gun, named "Long Cecil" in honour of Rhodes, was machined in the De Beers workshop from a 3 m long steel pump shaft. The gun took four weeks to construct and started firing its 13 kg shells on 23 January 1900. Labram was killed by a Boer shell shortly afterwards. The gun-carriege of Long Cecil was later used at Rhodes's funeral to transport his coffin, and now stands at the Union Buildings in Pretoria. The gun itself is in the Kimberley War Museum. The residential suburb Labram in Kimberley was named in his honour in 1952.