- Opal - Wikipedia
For use in jewellery, most opal is cut and polished to form a cabochon, a convex shape that maximises the viewing angles through which an opal's play of colour can be observed "Natural" opal refers to polished stones consisting wholly of precious opal
- Opal | Properties, Types Uses | Britannica
Opal, silica mineral extensively used as a gemstone, a submicrocrystalline variety of cristobalite In ancient times opal was included among the noble gems and was ranked second only to emerald by the Romans
- Opal Gemstone | Opal Stone – GIA
Opal is the product of seasonal rains that drenched dry ground in regions such as Australia’s semi-desert “Outback ” It is known for its unique display of flashing rainbow colors
- Pictures of Opal - Black, Fire, Boulder, Blue and Pink
Photos of opal from around the world Guidance for people who want to buy opal, see different types of opal, understand their names, learn about synthetics and imitations
- 14 Different Types Of Opal And What They All Look Like
Explore the vibrant world of gemstones! Learn about the different types of opal and where to find them in our comprehensive guide
- Opal Gems: Value, Price, and Jewelry Information - IGS
Opal gems are so unique you’ll need a special vocabulary to describe them Learn all about the many opal varieties and how to evaluate them
- Opal - The #1 Screen Time App
Real Focus in Real-Time Measure and improve your focus day by day, on iPhone, iPad and macOS
- Opal - New World Encyclopedia
Common opal is truly amorphous, but precious opal does have a structural element The word opal comes from the Sanskrit upala, the Greek opallios, and the Latin opalus, meaning "precious stone "
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