On 17 July 1852, the cutting began at the factory of Garrard & Co. in Haymarket, using a steam-powered mill built specially for the job by Maudslay, Sons and Field. Under the supervision of Prince Albert and the Duke of Wellington, and the technical direction of the queen's mineralogist, James Tennant, the cutting took thirty-eight days. Albert spent a total of £8,000 on the operation, which reduced the weight of the diamond from 186 old carats (191 modern carats or 38.2 g) to its current . The stone measures long, wide, and deep. Brilliant-cut diamonds usually have fifty-eight facets, but the Koh-i-Noor has eight additional "star" facets around the culet, making a total of sixty-six facets.