A COLOURED DIAMOND AND DIAMOND RING, BY SUWA
Designed as a cluster of vari-sized marquise-cut diamonds, accented by a pear-shaped fancy intense blue diamond weighing 1.25 carats, mounted in platinum, ring size 5¾, in black leather Suwa case
Signed Suwa, No. 109X4 Accompanied by report no. 15122499 dated 7 March 2008 from the Gemological Institute of America stating that the 1.25 carat diamond is fancy intense blue, natural colour, VS1 clarity
Also accompanied by a supplemental letter by the Gemological Institute of America stating the 1.25 carat diamond has been determined to be a type IIb. Type IIb diamonds are very rare in nature (from the laboratory's experience, less than one half of one percent) and contain small amounts of boron that can give rise to a blue or gray colouration. An unusual property of type IIb diamonds is that they are semi-conductors and conduct electricity. Historically, the ancient mines of India produced occasional blue diamonds but today the most significant source is limited to the Cullinan (formerly Premier) Mine in South Africa.
Among famous gem diamonds, the 70.21 carat Idol's Eye and the 45.52 carat Hope are examples of type IIb
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