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Opal

Opals from Mezezo, Ethiopia have been well-known for more than 10 years for their play-of-color chocolate opals. Other deposits discovered more recently from Welo yield precious white, fire, crystal and sometimes black opals. The opal you see here is an uncut crystal opal (643.9ct) from Welo. Gem opal consists of tiny silica spheres tightly packed together; the voids or spaces between the spheres contain air or water. The play-of-color in opal is due to the orderly arrangement of these spheres acting like a diffraction grating, breaking visible white light in to separate colors. Opals are typically cut en cabochon or polished free-form to best show the play-of-colors. This beautiful rough Ethiopian opal is a wonderful addition and upgrade to the National Gem Collection and the first from Welo.

Image Number: Ken Larsen
Weight: 643.9 carats
Gift of Opalinda and EyaOpal , 2009
Locality: Welo , Ethiopia

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Smithsonian National Museum of Natural History Department of Mineral Sciences website Credits