The Galaxy Opal is the world's largest polished
opal
Opal is a hydrated amorphous form of silicon dioxide, silica (SiO2·''n''H2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a ...
, 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 British reference book published annually, listi ...
in 1992. It was found at the
Boi Morto Mine in
Brazil
Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
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 s ...
and an approximation of its weight in carats had to be determined using a postal scale. The stone measures . It is currently part of a private collection.
See also
*
List of individual gemstones
A number of individual gemstones are famous in their own right, either because of their size and beauty or because of the people who owned or wore them.
Aquamarines
* Dom Pedro, the world's largest cut and polished aquamarine. It is currently h ...
Other notable individual opals:
*
Andamooka Opal
*
Flame Queen Opal
*
Halley's Comet Opal
*
Olympic Australis Opal
References
External links
Photograph of Galaxy Opal
Individual opals
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