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Lot Essay
Although this rough diamond is treated, the stone is still quite noteworthy - just in the fact that it is treated. To come across a treated rough diamond is rare, not only at auction but in the jewellery and diamond market as well. The rarity is due to the fact that treating rough diamonds is usually done so for the sole purpose of deceipt and profit.
Christie's, along with the owner, has the explicit desire and duty to alert people of this fraudulent process.
We would like to thank Tom Moses of GIA Research for contributing the following three paragraphs.
The cause of colour in most green diamonds and some green to blue diamonds is exposure to ionizing radiation either in nature or in the laboratory. In nature, this exposure occurs in the earth's crust after the diamond has been transported from the mantle to the near surface. This natural irradiation occurs over geological time as the diamond is exposed to radioactive elements. During natural irradiation, the diamond's surface turns green or blue-green, however, most of this colouration is usually shallow on the rough crystal. This phenomenon of naturally irradiated diamonds occurs in many locations, but has been reported with regularity in diamonds originating from the Jawang mine in Botswana and with diamonds from Brazil. It is very rare that any of this colour remains in a polished diamond.
Laboratory irradiation of diamonds was first reported in the early 1900s. At that time, the diamond to be treated was packed in radioactive compounds. This kind of irradiation produced a shallow green colour with a characteristic appearance. In the late 1940s diamond colour treatment became more commercial with the advent and use of particle accelerators. Innovations in the type of irradiation, radiation source, and in the precise irradiation process, continue to the present day. Historically, this type of treatment has been done almost exclusively to polished diamonds, although interestingly one of the first known treated diamonds was a small blue-green octahedral crystal. Sir William Crookes, a noted scientist and the pioneer of artificial colouration of diamonds, donated this crystal to the British Museuam in 1916. Some recent methods of laboratory irradiation, such as using a nuclear reactor, usually give rise to irradiated diamonds with more uniform colouration.
The 10.24 carat crystal was likely to have been a light brownish colour prior to treatment. In this case, the treatment does not penetrate through the crystal, but is confined to one side.
The Christie Hospital, in Manchester, England (incorporating the Paterson Institute for Cancer Research) is the largest integrated cancer centre in western Europe. Our major Millennium Exhibition "Treasures of the North", held at Christie's Great Rooms in January-February 2000, helped to raise over £200,000 for the Christie Cancer Hospital. The proceeds from this lot will be added to that sum.
Christie's, along with the owner, has the explicit desire and duty to alert people of this fraudulent process.
We would like to thank Tom Moses of GIA Research for contributing the following three paragraphs.
The cause of colour in most green diamonds and some green to blue diamonds is exposure to ionizing radiation either in nature or in the laboratory. In nature, this exposure occurs in the earth's crust after the diamond has been transported from the mantle to the near surface. This natural irradiation occurs over geological time as the diamond is exposed to radioactive elements. During natural irradiation, the diamond's surface turns green or blue-green, however, most of this colouration is usually shallow on the rough crystal. This phenomenon of naturally irradiated diamonds occurs in many locations, but has been reported with regularity in diamonds originating from the Jawang mine in Botswana and with diamonds from Brazil. It is very rare that any of this colour remains in a polished diamond.
Laboratory irradiation of diamonds was first reported in the early 1900s. At that time, the diamond to be treated was packed in radioactive compounds. This kind of irradiation produced a shallow green colour with a characteristic appearance. In the late 1940s diamond colour treatment became more commercial with the advent and use of particle accelerators. Innovations in the type of irradiation, radiation source, and in the precise irradiation process, continue to the present day. Historically, this type of treatment has been done almost exclusively to polished diamonds, although interestingly one of the first known treated diamonds was a small blue-green octahedral crystal. Sir William Crookes, a noted scientist and the pioneer of artificial colouration of diamonds, donated this crystal to the British Museuam in 1916. Some recent methods of laboratory irradiation, such as using a nuclear reactor, usually give rise to irradiated diamonds with more uniform colouration.
The 10.24 carat crystal was likely to have been a light brownish colour prior to treatment. In this case, the treatment does not penetrate through the crystal, but is confined to one side.
The Christie Hospital, in Manchester, England (incorporating the Paterson Institute for Cancer Research) is the largest integrated cancer centre in western Europe. Our major Millennium Exhibition "Treasures of the North", held at Christie's Great Rooms in January-February 2000, helped to raise over £200,000 for the Christie Cancer Hospital. The proceeds from this lot will be added to that sum.