How To Evaluate An Australian Black Opal?
Opal is one of the most valuable gemstones mined today. It is highly prized among collectors and designers cut into palm stones, into jewelry such as black opal earrings and vivid carvings.
You will find many types of opals around the world, but black opals are the most precious kind. Their dark body tone and vibrant play of colors make them incredibly valuable.
What Is An Australian Black Opal?
Black opals are actually rare to come by unless you are in Australia. Nearly 95% of all black opal is found in Australia alone. Australia's Lightning Ridge is considered the world capital of black opals, famous for producing large amounts of fine quality black opal. Lightning Ridge opal is also more highly-priced than others.
Black opal stone is characteristically known for its darker body tone, which can range from dark grey to jet black. This black color makes the shimmers of its inner rainbow even more vibrant and beautifying. Its rarity and intense beauty make it incredibly desirable and expensive. High-quality black opal may very well cost you over $10,000 per carat.
How to Evaluate a Black Opal?
You must always carefully examine a black opal before you purchase one. However, opals can be a bit difficult to evaluate at first glance. It helps if you mentally keep note of some factors as you give it a look. These factors determine the final price of your black opal.
Brightness
The black opals' brightness, also referred to as its “fire”, is the most important factor to consider. Brightness here refers to the vividness of colors in the opal. You will notice several levels of brightness in the opals you come across.
These are compared to the opal brightness scale, which ranges from Brilliant (B1) to Bright (B2-B3) to Subdued (B4-B7). The brightness (B) of your opal correlates directly to its price. The higher the brightness, the more its ultimate price will be. In short, opals that fall in the brilliant category (B1) are more sought after.
Darkness
Next, have a look at the opal's body tone. The body tone of the opal is the base tone of the background color that gives contrast to the opal's inner play of color. Black opals, therefore, have a much darker body tone.
You can study the body tone or darkness of the black opal stone by comparing it with the opal body tone chart. This chart ranges from N1 (jet black) to N9 (transparent). Black opals tend to fall under the N1-N4 range. This is followed by semi-black opals, which range from N5-N6. White opals are categorized last as N7-N9.
The darker an opal's body tone is, the more it will cost. This is why jet black opals are higher-priced gemstones.
Weight
Opals come in all shapes and sizes and therefore vary in weight. Their weight is usually measured in carats. You will notice that these gemstones are lighter and more comfortable to wear, even in larger sizes. This is because opal has a relatively low density (1.9-2.3 g/cm3). Just keep in mind that the more carats your opal weights, the more it will cost you.
Colors
Next, consider the color of your opal. Here we don't mean the body tone but the inner play of color. Play of color is an optical phenomenon occurring inside the gemstone when light strikes its surface. The light is reflected off the silica spheres inside the gemstone, causing a burst of bright colors against the surface of the stone, which can be seen quite vividly by the naked eye.
The type of color you want to see in your opal is an entirely personal choice. You will find mixed spectral lines of red, green and blue, which are the most valuable. Some people like green and blue colors more while others may prefer orange and red tones instead.
The more colors your gemstone has, the more it will cost you. For example, a gemstone portraying up to 15 colors will be more expensive than one with 3 colors.
Dome
Look at how the dome of your opal is shaped. Domed surfaces will allow your gemstone to appear more bright and vivid from all viewing angles. It will also make it less prone to breakage.
However, the stone may be more vulnerable to breakage if your opal dome is flat from the surface. If the dome is too high, it may be harder to mount in jewelry, such as a black opal engagement ring. Well-rounded domes are the ones you should be looking for. However, well-rounded domes are carefully cut by professionals, so you will find them to be a bit more expensive.
These were some of the most vital factors you need to keep in mind when evaluating a black opal. After all, it’s a black opal ring or black opal earrings; black opal jewelry is not a small investment.
