The Cullinan I diamond (The Great Star of Africa) that is set on the Imperial Cepter is here and there mentioned as the largest cut diamond in history.
Well it is not so, I’m afraid.
There is a larger cut gem quality diamond, but not in the British Crown jewels. The Golden Jubilee diamond in the Thai Royal Treasure weighing 545.65 ct (15.45 ct more than Cullinan I at 530.20 ct) and with over 5 cm in length (55.65 x 49.20 x 34.25 mm) is, in fact, the largest cut gem diamond on record.
It is a Fancy yellow-brown stone cut in Johannesburg, South Africa, between 1988 and 1991 under the supervision of master Gabriel S. Tolkowsky (1939-2023) in his proprietary Fire Rose cut, with a total of 148 facets (55 crown, 69 pavilion and 14 girdle).
The rough, a massive 755.50 ct brown, was found in 1986 at the then called Premier mine (now Cullinan mine) in South Africa. The cutting process was instrumental to test the equipment that would be used in the fashioning of the D-colour 273.85 ct Centenary diamond. The yield (weight of the cut stone that is retained compared to the weight of its original rough) is remarkable at over 70% (<30% weight loss).
The diamond was originally known as the Unnamed Brown until 1995 when De Beers Group sold it to a Thai consortium lead by Henry Ho that would offer it to late King Bhumibol of Thailand (1927-2016) on the Golden Jubilee of his reign, hence the name, being currently in the Royal Treasury in Bangkok.
Guest articles by Rui Galopim de Carvalho:
https://gem-spectrum.com/category/rui-galopim-de-carvalho
About the author:
Rui Galopim de Carvalho is a renowned independent Gem Education Consultant, author, luxury industry training expert and popular international lecturer on gemmology and on the history of gem materials. During his 30 year experience as a gemmologist, Rui has studied important collections in both public and private museums, notably the Portuguese Crown Jewels.
Founder of the popular Home Gemmology webinar series launched during the COVID-19 lockdown, Rui has a long history as a gemmology communicator, notably on social media where he is a popular figure.
He is associate editor of Gem-A’s Journal of Gemmology, Vice-President of the Coral Commission of The World Jewellery Confederation – CIBJO, member of the Communications Committee of ICA (International Colored Gemstone Association), ambassador for LAUREL -Portuguese Association of Excellence Brands (ECCIA member) and consultant for several private collections and trade organizations.
Rui Galopim de Carvalho can be reached through his website:
Articles about Thailand:
https://gem-spectrum.com/tag/thailand
