I too was concerned about the sharpness of Caroline's wedding ring and your post got me thinking, Kathleen. Caroline's ring is an "enormous fire opal oval surrounded by six smaller diamonds," (p. 61). Opals usually have smooth surfaces and are not cut like other gems. Also, when I re-read that part of Chapter 6, it occurred to me that Caroline's ring was specifically a fire opal. The image I have of an opal is the pearly white with lots of pink, blue, and purple colors in it, so I did a search on Google and found that fire opals are quite different!

Fire opal breaks all the rules for opal. Opal is a gem valued for its play of color, the shifting light showing through from its depths. Body color is only a backdrop for the main attraction. But the color of fire opal is hard to ignore: hot yellows, oranges, and reds so bright they look as though they might glow in the dark. Fire opal sometimes does have play of color but it does not need this to take a starring role in jewelry. Source: http://www.gemstone.org/gem-by-gem/english/fire.html

Furthermore, I also learned that opals have a lot of superstition and myths connected to it. Some people consider it lucky and others bad luck. For example, the Romans consider opals to be lucky while the Australian aborigines thought the opal represented something evil. Lots of people today also think that to wear is opal is something to be avoided unless it is your birthstone (October).

One other website I visited mentioned that opals are very powerful in ritual magic. Because it contains the colors of all other gemstones, it can be charged with all the powers of the other stones. Opals have been linked with the notion that it renders the wearer invisible, and has been used to bolster mental capacities, such as increased and creative imagination.