The 203.04-carat D flawless De Beers Millennium Star was cut from a rough diamond of 777 carats. It was unveiled in 1999 at the Millennium Dome where it became the target of a foiled robbery attempt in 2000.
This 203.04-carat pear-shaped stone is the world’s largest ‘D colour’ internally and externally flawless diamond. White diamonds are graded by colour using a lettering system from D to Z, with D being completely colourless and Z a pale yellow. This is the sixth largest ‘white’ diamond in the world.
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Brightness is the amount of white light returned to the observer according to GIA and American Gem Society (AGS)
In the trade brightness is often called brilliance
According to Pagel-Theisen's book " Diamond Grading ABC " the term "brilliance" involves several distinct optical processes in a diamond as follows:
1) Internal Brilliance
2) External Brilliance (lustre)
3) Dispersive Brilliance (fire)
4) Scintillation Brilliance ( sparkle) ( Pages 176-177)
AGS defines brilliance as " brightness plus positive contrast" in other words a brilliant diamond appears bright "with an attractive distribution of contrasting dark and bright areas"
According to Renee Newman GG in her " Diamond Handbook" Revised 2nd Edition 2008 Page 13 uses brightness " to specifically refer to the intensity of internal and external light return".
Renee continues " Diamond has a greater potential for brightness than any other natural gemstone. This is because of diamond's extreme hardness [resistance to scratching], adamantine luster [lustre],lack of colour and high refractive index ( the degree to which light is bent as it passes through the stone[diamond].The proportions,polish,transparency,colour and clarity of the diamond all affect it's brightness"
In the trade brightness is often called brilliance
According to Pagel-Theisen's book " Diamond Grading ABC " the term "brilliance" involves several distinct optical processes in a diamond as follows:
1) Internal Brilliance
2) External Brilliance (lustre)
3) Dispersive Brilliance (fire)
4) Scintillation Brilliance ( sparkle) ( Pages 176-177)
AGS defines brilliance as " brightness plus positive contrast" in other words a brilliant diamond appears bright "with an attractive distribution of contrasting dark and bright areas"
According to Renee Newman GG in her " Diamond Handbook" Revised 2nd Edition 2008 Page 13 uses brightness " to specifically refer to the intensity of internal and external light return".
Renee continues " Diamond has a greater potential for brightness than any other natural gemstone. This is because of diamond's extreme hardness [resistance to scratching], adamantine luster [lustre],lack of colour and high refractive index ( the degree to which light is bent as it passes through the stone[diamond].The proportions,polish,transparency,colour and clarity of the diamond all affect it's brightness"
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" Diamond Handbook " by Renee Newman GG
A Practical Guide to Diamond Evaluation
Completely Revised 2nd Edition 2008
AUD$24.50 GST inclusive
To Order Email guru@diamondimports.com.au
__________________________________
***
" Diamond Handbook " by Renee Newman GG
A Practical Guide to Diamond Evaluation
Completely Revised 2nd Edition 2008
AUD$24.50 GST inclusive
To Order Email guru@diamondimports.com.au
__________________________________
***
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