Opal comes in many forms and from many places. It can be white with very little color (what most people know), clear crystal and a flash of color (mall jewelry), orange Mexican fire opal or the rare black opal. It can be a dull blue opal, a green-blue opal or a fiery multicolor stone that dances like no other gemstone. It can be from Hungry, Peru, Mexico, Nevada, Australia, Brazil, Honduras, or even now "chocolate" from Ethiopia. All of these varieties can run from dull (no color) to some specs of color, to flakes, to flashes and to just solid single colors. It can appear to be a simple rock or the brightest, liveliest stone you have ever seen. All of these diverse factors make this discussion very complex and confusing for most people.
In addition to solid, natural opals (which will be my focus), opals are solid as doublets (or doublets), triplets, mosaics, lab created and even simulated. This makes it even more difficult for the consumer. I will attempt to make it simple and understandable. I will attempt to present the meaningful discussion of the factors which govern the pricing and evaluation methods that are used by the opal industry and dealers when selling loose opals or finished jewelry. My focus will be on valuation of solid natural Australian opals with visibly displayed color, called precious opal. My opinion of opal is it must have an appearance that is visibly appreciative, that is unique, eye catching and will look good in a jewelry mounting. If you want plain dull white opal buy pearls at least they shine. If you want black opal with no color then buy onyx at least it shines as well. A complete guide to opal identification and valuation would take 200+ pages and many hundreds of photos. We will present a concise but complete description of the process so a layman and a jeweler can have the information they need to make an informative buying decision. Opal identification and valuation is not standard there are no industry guidelines like for diamonds and many colored stones. Even most laboratory and Gemologists cannot correctly identify or evaluate an opal, it is left up to "field" experts, the market and opal dealers to set the trend and educate the public on the complex nature and methodology of opal valuation. Evaluating and pricing an opal is more difficult than any other colored stones especially diamond. So lets get started and if you do not understand or you need more detailed information please e-mail us or call us toll free in the USA (800) 376-6725. Below are the sections we will focus on.
Opals are unique and no two are exactly alike. All types come in various shapes, colors and qualities. Important factors in choosing and valuing an opal are.
Opals like diamonds are measured by carat weight. Quality opal can command a price per carat similar to that of diamonds.
Generally opal size and shape pertains to the opals value for jewelry use. A calibrated oval gemmy stone 1 to 3cts will have the most value for rings and earrings while a 3 to 5cts+ may be more valued for pendants. Opals that are not a standard shape such as oval, pear, heart, round, or marquise are called "freeform". These have less value when appraised but to the right customer and jewelry designer a freeform opal offers unique possibilities for custom designed jewelry. Opals can also be custom cut (by our company) from rough opal into any shape to fit the designs. Larger opals even of high quality is great for big pendants and collectors as keepsakes but are usually difficult to sell. On a per carat basis a 5ct black opal with red multicolor has more value than a 25ct stone too big to set into jewelry. The shape and size can also affect the cut quality valuation. A stone should have a good thickness for setting and wearability. The dome height of an opal also helps display or disperses colors better than a low dome stone. The quality of the polish will also determine how much reflection you get. The next subject, color/directionality determine a major factor of cost.
The beauty of an opal is in its color and generally speaking, the more colors in an opal, the more valuable the stone. How the colors are displayed and move represents the patterns.
Opal colors literally transverse the rainbow but the major color combinations are blues/greens and multicolors. The more reds with any of these color combinations the higher the value, and in multicolors opals the more variation of opal the more value. Some opals also have only one color such as green, blue. Orange, or yellow. Of course opal colors to the buyer is what is most important- some people only like blue/green opals, while others love the wide variety of a red multicolor opal. Now there is a blue/green Peruvian opal that has no fire.
A clear opal with rich vibrant colors will be highly valued. An opal with inclusions or opaque patches will not be as valuable as a clear stone. White opal is sometimes called "milky opal" due to its translucent to opaque whiteness, which can have all traditional colors against this white background.
Mexican fire opal in reality is just orange, yellow, red, or a combination of body color and does not have "fire" or flashes like most opal. There is a type of Mexican opal with intense red, orange, green, yellow, and sometimes blue flashes that come from inside the stone. This is highly prized and can fetch thousands of dollars per carat. The problem with most Mexican opal is the "stability"- many times the opal crazes or cracks 6 months after you buy it. That is why Opals International keeps all its opal uncut for up to a year before selling and then offers a one year industry exclusive guarantee against natural crazing and cracking so the type of colors, variation of color and intensity of color plays a major factor in opal valuation.
The base or body color determine the first factor-type- most common white opal or light opal which can display all the colors of the rainbow on a pale background. The terms red orange and green "fire" describe the dominant color of the stone. White opal generally comes from Coober Pedy and Mintable in South Australia. Opal of this nature can be 0.50$ per carat and up to $500 per carat for top gem full fire.
Crystal/semi-crystal opal merely means that when held up to light you may see through the stone. But a good crystal opal from South Australia Coober Pedy or even Lightning Ridge (home of the black opal) should display a blue-green color pattern or multicolor. Most of the very bright gem grade opals on our website are crystal opals. Some of the finest opals ever found were Top Gem crystal opals displaying vibrant red multicolor flashes that dance with the stone, along with every other color imaginable crystal opal is transparent with a sharp difference in diffracted color from inside the surface of the opal. Most of the inlay jewelry on our site and Kabana use very bright blue/green crystal with epoxy enhanced background. Crystal opals with good color are priced from $200/carat to $3000/carat for top gem multicolor opals.
Boulder opals are usually a brown base with "thin" color veins splashed across or through the opal and ironstone matrix. Most of these opals come from Queensland, Australia. Boulder opals typically are blue-green in color but can also have in rare cases multicolored patterns the same as crystal opals. The trick is to cut the color section in a way that can maximize the opals appearance. Boulder opals are typically "freeform" shapes in nature and can be quite large. Boulder opal is a solid opal, which consists of a fine layer of opal that has been deposited naturally on and in the fissures of ironstone rock. The gem opal is usually filling crevices and cracks within the ironstone matrix. Boulder opal can be extremely bright and interesting. A favorite of gem and jewelry designers often being a part of Award Winning Artistic Designs. Very bright, large multicolored boulder opals are extremely rare. Most common boulder opals of any value are a blush-green in nature and freeform shapes.
Black opal comes primarily from Lightning Ridge, New South Wales Australia. Some black opal is also found in Nevada as a form of fossilized tree limb, but stubble gem grade material from Nevada is rare. Technically black opal has a dark body color and can range from jet black to a gray-black background. Because of the darker base the colors reflect stronger and are highly sought after due to the rarity and beauty of the black opal. The brighter, more unusual and sharper/vivid the colors the more valuable. In the same mining area, a form of Top Gem Crystal with a darker background can be found which is considered the best crystal opal hands down, called "Black Crystal". It is very dark, very bright, all colors, vivid, and if you hold it up to light you can see through it, but placed in jewelry you see nothing but color. Most black opal is a blush-green color but can be any combination including gold, violet, yellow, and orange. Probably the rarest of all gems including fancy color diamonds is a very black, dark background with reds/pinks and other colors splashed across the stone with intense brightness and a "dance" that no stone can match. The top stones of this description can fetch $40,000 or more per carat. A Harlequin pattern black opal is so rare that it can be compared to a red diamond. Valuation of black opal with just blue will run from $100 to $500/carat. As you add green the price goes up. The darker the stone the more money, the brighter and more reds the more money. Nice stones less than 5cts run from $2000/ct to $5000/ct. The patterns can increase values dramatically.
This refers to how the opal exhibits colors/patterns and brightness from various angles. A perfect opal is not directional meaning you can see colors/patterns at all angles as you look at it. This is most prized but not most common. It seems even in bright stones that at some angles the stone looses its life that is why some stones are perfect for pendants and earrings in one orientation, and should be tested for viewing quality in all of these orientations before buying. Other stones are perfect for rings, as the stones look great in all angles. A stone that only looks good at one angle should have much less value than a similar stone that is great at all angles. And of course there are varying degrees of "directionality". Along with this discussion the lighting situation should be considered. In jewelry stores bright halogens can make almost anything look good but in the case of opals, softer lights, darker light can often have a dramatic effect on how your opal looks. All opals should be viewed in florescent light as well as natural light to see how it looks. An opal stone that looks good in all lighting will be the most valuable, while a stone that needs lots of direct light to display colors will not be as prized. Next we will discuss opal brightness and how it is measured, probably the single most important factor in determining value.
J. Thomson Custom Jewelers