Precious opal is a gorgeous gemstone which shows ‘play of colour’, that is, iridescent colours can be seen inside the stone when it is moved. Precious opal includes black opal, white opal, crystal opal, boulder opal and matrix opal. There is a common opal which does not display ‘play of colour’.
Today, Australia is the world’s biggest producer of opals, producing approx 95% of the world’s supply. Historically, though, opals were mined at Czernewitza in Hungary (in what is now Slovakia). Opal found in antique jewellery was also mined in Honduras and Mexico and from the USA from the late 19th century.
Popular with the Romans and for a number of centuries following, opals became associated with bad luck from the late 17th century until the middle to late 19th century. They became popular again with the rise of Art Nouveau and Belle Epoque jewellery. Edwardians used a lot of opals in their jewellery. A typical example is the fabulous necklace pictured at the top of the post.
In antique jewellery, the most common precious opals found were either white opals or crystal (or water) opals. White opals have a white or creamy background with play of colour. A crystal or water opal refers to any kind of opal which has a transparent, translucent, or semi-translucent body.
Australian white opals can be found in Australian-made and some English-made jewellery from the 1890s onwards and black opals in the early 20th century. Black opals were not commercially mined until 1903.
Opals are quite soft and can crack easily so are best suited for earrings, pendants and brooches but we do see them used in rings and bracelets. They are usually cut as cabochons.