Though often referred to as a precious stone when set in jewelry, such as in opal ring, this gem is actually a mineral meaning that it is not comprised of crystals. It naturally occurs within the fissures of rocks, especially sandstone, limonite and basalt thus it is generally found in areas where these rocks are present. Australia currently produces around ninety five percent of all of the world’s opals. Opals actually have very high water content, anywhere up to twenty percent although it is normally anywhere from three to ten percent. This relatively high content of water makes opals fairly sensitive and care has to be taken not to cause damage to them.
While opals are not crystalline in nature they are made up of silica spheres and it is the passage of light through these spheres that gives the opal its coloring and brilliance. The more regular the spheres the higher the quality of the opal is. The best opals show a magnificent play of color, in part caused by small micro-fractures inside the formed opal also filling with silica. There are two main ways in which opals, that are too thin to be used on their own, are prepared as a gemstone. A thin layer of is opal backed by a darker stone which enhances the play of color on the stone; this is referred to as a doublet opal. A triplet opal backs the opal layer with black material and then covers the dome of the opal with clear plastic or quartz. This clear layer both protects the opal and magnifies the design, however because of the artificiality of the triplet opal it is not considered a gemstone, although it is frequently still used in jewelry.
When determining the value of the opal, there are several things to take into consideration. Of course, the main consideration is whether the opal is solid, or if it is a doublet or triplet. Naturally, solid opals are worth far more. Opals with a black background, rather than a gray or off white background are also much more valued mainly because it better displays the myriad of colors. The play of color, as mentioned above, is also a major determining factor in the worth of an opal. A red, or fire opal, is the scarcest and as such of higher value than the blue or green opals. Other things to consider are the brilliance of the colors, the pattern and the color bars in the opals.
Opals are usually used for earrings and pendants. These pieces of jewelry rarely come in contact with other surfaces, thus the soft opal is protected from getting scratched or damaged. Opal rings, on the other hand, need to be well cared for especially if they are worn on a regular basis. This is the reason why opal engagement rings are not necessarily the best as they are worn continuously. Wedding or engagement rings set with opals will need special care. For example they should be taken off before hands are immersed in water, as opals tends to absorb water. They should also be taken off before gardening, doing any carpentry tasks and before playing sports or swimming. It is also important, if worn in a dry hot climate, to take care, as opals will easily crack if exposed to too much heat, or if they experience a sudden change of temperature.
In spite of the care that must be taken with rings set with opals, they do look stunningly beautiful. Opals have been known to contain all the colors of the color spectrum. You can find them in any color from gray or off white to black, including all shades of color in-between. Of all of the colors, red opals are the rarest. White and green opals are by far the more common. Fire opal rings are some of the most sought after, and the most expensive type of rings set with opals. A fire opal ring is sometimes called a Mexican opal ring. Black opals are also extremely rare and thus a black opal ring may be very expensive to buy, fetching prices in the thousands of dollars, especially if it is set with other precious stones such as diamonds.
An opal ring is interchangeably set in either gold or silver bands, oftentimes depending on the color of the opal itself. A gold opal ring looks best with the blue and green opals, as well as the fire opals. A black opal, on the other hand, looks beautiful when set in silver or white gold. When buying opals it is best to buy from a recognized dealer. It can be very difficult to accurately determine the worth of an opal and there are also many imitations and artificial opals on the market. If you are planning to buy an expensive gold opal ring, you do want to ensure that the opal set in the ring is of optimum quality.