| Honorific Prefix: | Sir |
| Thomas Cullinan | |
| Birth Date: | 12 February 1862 |
| Birth Place: | Elands Post near Seymore, Cape Colony |
| Death Place: | South Africa |
| Nationality: | South African |
| Occupation: | Diamond mine owner, miner |
| Known For: | Namesake of the Cullinan Diamond |
| Children: | 10 |
| Relatives: | Patrick Cullinan (grandson) |
Sir Thomas Cullinan (12 February 186223 August 1936) was a South African diamond magnate. He is renowned for giving his name to the Cullinan Diamond, the largest diamond ever discovered, and as owner of the Premier Mine, now renamed the Cullinan Mine, from which the famous gem was extracted on 26 January 1905. He also gave his name to the nearby South African town of Cullinan. He was honoured by the African Methodist Episcopal Church in Tembisa which named their church after him (Sir Thomas Cullinan AME Church).
Of Irish descent, Thomas Cullinan was born in Elands Post near Seymore, Cape Colony on 12 February 1862.[1] He moved to Barberton in 1884 and married two years later. In 1887, he moved to Johannesburg.[2] There he became a bricklayer, and after he earned some money, he turned to prospecting. In 1897 he moved to Parktown, the up-and-coming suburb of the Randlords and had The View, his home, built. He discovered the Premier diamond fields in 1898. They lay a considerable distance from the existing diamond fields, but from the find of a diamond on the surface near a farm fence, he deduced that the diamond (found in alluvial soil) must have been washed from some higher diamond-bearing geological position. Such a position presented itself in the shape of a nearby koppie, which concealed a diamond-bearing blue ground pipe.
The owner of the mine, Joachim Prinsloo, had sold land to both gold and diamond prospectors before, and would not sell. However Cullinan succeeded in purchasing the land for £52,000 from Prinsloo's daughter, who inherited the farm after her father's death.[3]
Cullinan was one of the co-founders and chairman of what became the Transvaal Chamber of Industries.[4] He was a member of the Transvaal Legislative Assembly and the first Union Parliament of 1910,[4] representing the Pretoria Western district.[2]
He was knighted in 1910, at the inauguration of the Union of South Africa, in recognition of his contribution to industrial development in South Africa.[2] The investiture was carried out by the Duke of Connaught, representing King George V.[5]
Sir Thomas Cullinan died in 1936, aged 74.
He had a family of ten children,[2] and was the grandfather of Patrick Cullinan, a prominent South African poet.