The Galaxy Opal is the world's largest polished
opal
Opal is a hydrated amorphous form of silica (SiO2·''n''H2O); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Due to its amorphous property, it is classified as a mineraloid, unlike crystalline forms o ...
, certified by the
Guinness Book of World Records
''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a reference book published annually, listing world ...
in 1992.
["The Guinness book of records, 1993" October 1992, ]
p.22
/ref> It was found at the Boi Morto Mine in Brazil in 1976. The finished opal weighs approximately 3,749 carats, or 0.75 kg. It was carved from a grapefruit-sized piece of rough stone weighing 5,205 carats by Scott Cooley into a shape resembling a child's head. The weight of the finished stone was beyond the capacity of any gem measuring scale at the Gemological Institute of America
The Gemological Institute of America (GIA) is a nonprofit institute based in Carlsbad, California. It is dedicated to research and education in the field of gemology and the jewelry arts. Founded in 1931, GIA's mission is to protect buyers and se ...
and an approximation of its weight in carats had to be determined using a postal scale. The stone measures 14.0 x 10.2 x 4.1 cm (5-1/2 x 4 x 1-5/8 in). It is currently part of a private collection.
See also
* List of individual gemstones
A number of gemstones have gained fame, either because of their size and beauty or because of the people who owned or wore them.
A list of famous gemstones follows.
Alexandrites
* Smithsonian museums' Alexandrite, the largest cut alexandrite ...
Other notable individual opals:
* Andamooka Opal
* Flame Queen Opal
* Glorious Jubilee
* Halley's Comet Opal
The Halley's Comet Opal is the largest uncut black opal in the world, according to the Guinness Book of World Records. It is so named because it was unearthed in 1986, a year when Halley's Comet could be seen from Earth. It is the third largest gem ...
* Olympic Australis Opal The Olympic Australis opal is the largest and most valuable opal yet found () and was valued at in 1997. It was found in 1956 at the 'Eight Mile' opal field near the town of Coober Pedy in South Australia.
The opal was found at a depth of . The ...
References
{{Reflist
External links
Photograph of Galaxy Opal
Individual opals
Individual gemstones