Hi thank you for writing in. Before 1906 karat marking was not compulsory so many pieces of antique gold jewelry are not marked.
However, gold plating was also introduced in the mid 1800s. Some electroplated pieces were marked GOLD. First thing is to ascertain whether the gold is solid gold or electroplated. Look carefully at the inside of the ring with a magnifying glass or a jewelers loupe with at least 10x magnification.
If it is gold plated you should be able to detect a change of color, this is especially evident if the ring is gold or silver electroplated over brass or copper. Let me know how you get on.
In 1870 a HUGE opal field was discovered in Australia which prompted Queen Victorian to try again to lift the veil of superstition that had plagued this beautiful gemstone. It was one of Queen Victoria's favorite stones. She gave them as wedding gifts to her daughters and wore opals herself.
By 1886 opals had lost their unlucky reputation and were being used in the latest designs. In an article in the August 1886 edition of Godey's Lady's Book reported:
"During the last few years, a reaction has taken place and American women are accepting the magic gem.."
On both sides of the pond from 1880s Opal Jewelry was highly fashionable.
Please do attach a photo of your antique opal ring in a follow-up submission, we'd love to have a look!