Opals of all different colors are and have different values depending on the color it displays.
You can categorize opals by using the color that is more dominant in the opal as the first name of the opal for example. (Green blue opal) A green blue opal means that the opal has a main color base of green than blue, because the name green comes first. Just as the opal blue green or green orange or orange green or red orange or orange red. These categories are assed by the human eye and an experienced opal dealer can tell you what category the opal will be in.
By categorizing the opal in this way we can discover the different types and qualities of opal there are. Bodytone and brightness are a totally different part of the categorization. And cant be confused with the color categories.
Green Blue opal is the 3rd most common type of color in opal after blue opal and blue green opal. As confusing as this may sound it does make sense.
Green blue opal in the 90s was the opal considered the commercial opal and would be sold in parcel along with the red on black opals that we find in Lightning Ridge. These opals are now very rare and values are on the increase every year. The green blue opal can be found in Coober Pedy, Andamooka, White Cliffs, Lightning Ridge and in the Queensland opal fields as well. Some New deposits of volcanic opal like Ethiopia have green blue opal as well which have hit the market with great viscosity and little was known of it stability. Now it has been on the market for a while we have found the new deposit to be very unstable and unreliable. Not to mention unethical to mine.
My favorite type of opal is the green blue color as they are my favorite colors to wear. When you put a green blue opal in front of me and also a red I will choose the green blue every time.