The Dolmen de Mont Ubé in St Clement, which is owned by the Société Jersiaise, was vandalised last month. A police investigation was launched and the two 14-year-old culprits spoken to, although no further action was taken.
On Wednesday stonemasons Granite Le Pelley removed the graffiti using a high pressure washer capable of blasting water at up to 150°C.
Robert Waterhouse, the history society’s field archaeologist, said that he was pleased with the results and that he believed that the incident was a ‘silly one-off’.
He said: ‘We would like to thank Granite Le Pelley for doing this for free and also the owners of the adjoining house who supplied copious amounts of water for the washers. We are very happy with the result.’
