Let’s discuss natural solid opals. These are the opals mined from the ground. These rough chunks are cut into one solid piece of opal. These are referred to as natural solid opals. There are three subgroups of opals: Precious Opals, Fire Opals, and the Common Opals.
Precious Opals
White Opals and Black Opals
There are white opals and black opals. The color refers to the main background (base) color of the opal, not the play of color inside the stone. A better description is light and dark opals, but we are stuck with white opals and black opals. The reason I say this is because the background colors can range from black, white, dark blue, dark green and the whole range of greys. The white opal has a white background or a light color background that contains play of color. The black opal also has a play of color on a dark grey, dark blue, dark green, and deep black background.
The picture below shows a loose white opal. This is the same opal from four different angles. Notice the stone’s background (base) color is white. This stone was acquired at a yard sale with the doublet pin and triplet earrings in Article 2 of this series. The seller gave me all 4 pieces free. If you want to know the trick I used, read the Silver Horseshoe Pin Lesson blog post.
Loose White Opal with different views of its fire. This is the same opal, but from different angles. Notice how the fire pattern changes when viewed at the different angles. This opal was given to me for free at a yard sale.
Keep in mind, black opals are rarer than white opals. If all characteristics are equal, the black opal would be more expensive. However, if the play of color is better (it contains rarer colors) in the white opal, than the black opal, the white opal could be worth more.
Crystal Opals
Don’t confuse the name crystal opal, with a quartz crystal. It is a real opal, but it is transparent to semi-transparent. You can see through it. There are white crystal opals and black crystal opals, which refers to the transparent base color (is it light or dark). If the opal is clear enough to read through when place on a light background and the play of colors show against a dark background, then it is a crystal opal. In theory, the values of the stones are from highest to lowest: Black Opal, Crystal Opal, and White Opal (providing all characteristics are the same, which we know no two opals are the same – so this is in theory).
This is a picture of my white crystal opal pendant. When I placed it on a book with light pages, I can read through it. The green play of color comes to life when I place it on a dark background. I didn’t get this pendant at a yard sale, it was given to me as a gift (just so you guys know), but I wanted to show it to you.
White Crystal Opal Pendant. It looks a little blue, because you are seeing the black background color showing through the transparent nature of the opal. It has a green fire in the opal, but it didn't turn out in the photograph.
Fire Opals
The fire opal is orange and usually shows no play of color. There are a few exceptions that have a rare flash of green. They can be milky and turbid. However, the best ones are clear and transparent. Because of this clarity, they can be faceted (like a ruby is faceted).
Common Opals
Common opals have no play of color. They are opaque and rarely transparent. They are also known as Potch. The potch opals can display the opalescence quality, but not a play of color inside it.
Want to read the fourth and final article in the Opal Series, where we discuss the characteristics of opals, read it here. In case you missed the second article in the series, you can read it here – Opal Doublets and Triplets. If you missed the first article in the opal series, you can read it here – Imitations, Not Gemstone Quality and Synthetic Opals.
Good Luck and Happy Hunting,
~Vicki Priebe Author of "Cheap Gold and Silver"