Opals can contain every color of the rainbow within them. Blue, Green, Purple, Pink, Yellow, Red, Orange, and everything in between. Sometimes individually, sometimes with just a few and sometimes with all colors within the one cut opal. These array of different colors is one of the main reasons why every single opal is unique.
Colors have formed over millions of years within an opals silica spheres. These are formed the same way as a rainbow is formed by light refraction, only with an opal the colors are trapped within the silica spheres forever. You might say that they are solid rainbows that never disappear!
An opals color, or array of colors is a huge contributing factor in determining the value of an opal. Traditionally red is valued as the most valuable color in opals, and this is because it is the rarest of colors in opals. You can watch the video here that explains why this is. Red opals can demand a much higher price tag than other colors in the market, and often a cutter or miner will get very excited when they expose any sort of red color whilst working.
Blue is often the most common color to find when opal mining. For some reason, this is especially the case with boulder opals. Blue is definitely the most common color in boulder opals and is very evident when you go to a place like Winton at their annual opal show; you will see a lot of lower grade blue boulder opal for sale.
Why is blue the most common color? This is because the color blue is at the other end of the color spectrum to red. Please watch the video to understand why this is! That being said, there is a specific type of royal blue that is very rare to come across and is second rarest in color to red. These opals can also demand a high price in the market.
Other rare colors in opals are metallic neon colors, as well as unique combinations of colors. It can be determined if a color is rare just by observing an opal in comparison to other opals in the market. When you work with opals a lot, you will begin to understand and identify easily what a unique, rare colored / patterned opal looks like.
The brightness of an opals colors is also very important in its value. There are many instances where you can find red in an opal, however its brightness is very low, so the value will still remain low. Rarer colors need to be discovered with good brightness in them to make an opals value high. Without good brightness, the colors contributing factor to value becomes somewhat irrelevant.
This is also the case with patterns. Unique, rare patterns are important in determining an opals value, however it is very important that these patterns also include an array of bright colors. Especially rarer colors are important. A bright red harlequin pattern will be more valuable than a mediocre brightness blue and green harlequin pattern. Brightness, Pattern and Color needs to work simultaneously to contribute to the value of an opal.