"In the nineteenth century, opal was considered unlucky due to
the plot of a popular Sir Walter Scott novel of the time. The
heroine of the novel has her life force caught in the beautiful
opal she wears in her hair and she dies when the fire in the opal
is extinguished." from the International Colored Gemstone
The novel mentioned is Sir Walter Scott's "Anne of Geierstein"...
Another opal story I've heard is that wearing an opal is bad luck
unless you were born in October...
If you want to get a fun book about gemestone lore, find a copy of
"The Curious Lore of Precious Stones" by George Fredrick Kunz (named
kunzite after him)...
Gary W. Bourbonais