The Opals can vary a lot in terms of appearance and quality. They can all be so diverse and noticeably different from each other. With the help of these quality factors, we can evaluate the value of the opals. The three main aspects of the Opal's quality are color, pattern, and clarity. We will discuss them in detail in this blog.
Evaluation of the Opals
The process of Opal Evaluation should be done carefully under controlled lighting on a dark background. While determining the type of opal and evaluating its cut and play-of-color, you should rotate it against the background. It helps to see the details correctly.
Five steps for the Evaluation
1. Recognise the type of opal and the base colour:
It includes that you should determine the base color of the opal, such as black opal, Crystal Opal, or White opal.
2. Gather the information about the play-of-color and its ratio
Things to consider include the ratio of background color to its play-of-color on the surface, as well as the range of color, pattern, intensity, etc.
3. The transparency of the Opal is essential:
Know about the opal's transparency, whether it is transparent, translucent, opaque, semi-transparent, or semi-translucent.
4. Determine the clarity of the Opal:
You have to look for any presence of crazing, pits, matrix, etc.
5. Find out the Opal's cut:
In this process, determine the opal's symmetry, polish, thickness, calibration, and sizing.
Different Factors that affect the quality of Opals
Many factors are involved and affect the quality of the opals. In this section, we will briefly discuss these factors to enhance our understanding.
Opal Colors
The colors of an opal gemstone can vary across the spectrum. It can display a single, double, or all the colors of the rainbow. Opals have a background color along with the play-of-color on the surface. This body color on an Opal stone is caused by the suspension of small impurities with silica spheres of opal. Opas are often divided based on their background color. Although there can be so many of them, here are the main five types with different opal hues:
Black Opal:
The black Opals are very famous among buyers, despite having the same opal quality factors. The reason behind this is the play of color that stands out in the black background, and the contrast looks beautiful. This makes the stone very attractive and increases its value. Additionally, the black opal is considered to be the rarest stone.
White Opal:
The white opal has a translucent to opaque white color or any other light color in the background of the stone with a play-of-color. The white opals are very common to find, and hence their value is comparatively less.
Fire Opal:
Fire Opal has a transparent to translucent body color which is usually orange, red, and yellow. If any Fire opal shows a play-of-color, then it is traded by the name "Mexican Opal" or "Mexican Fire Opal".
Crystal and Water Opal:
The Crystal Opal has a clear background, and they are somewhere between transparent and semi-transparent. These opals are capable of showing a brilliant play-of-color. The Water Opal, on the other hand, might or might not display any play-of-color. If they show play-of-color, then it will be very faint and only covers the small portions of the gem.
Boulder Opal:
These are translucent to opaque opals with a beautiful play-of-color within the host rock. This phenomenon is known as Matrix, in which the thin layers of opal are present within the host rock. The Boulder Opal is cut and finished with the matrix, and also becomes part of the finished gem.
Opal Patterns
Most of the artists prefer the large and closely arranged patches of color with scattered dots. In the context of play-of-color, regardless of the stone's pattern, the colors should be vibrant and bright for the gem to be valuable. Apart from the Opal pattern and play of color, the buyers also look for the dead spots on the stones. The dead spots are those spots in which there is no play-of-color, and the background is completely visible. These types of opals do not look very attractive, and their value is also lower. The Opal patterns mostly represent the arrangement of its play-of-color, and they can take many forms, many cloud-like shapes, and other patterns, such as:
Flame: There are kinds of sweeping reddish bands or long streaks that shoot across the stone.
Peacock: It contains the color patterns of blue and green.
Pinfire or Pinpoint: They are the small and closely set patches of colors.
Harlequin or Mosaic: They are the broad and angular patches of color that are set closely.
Opal Transparency and Clarity
In an opal, the clarity represents its degree of transparency and freedom from inclusions. The opal's clarity can vary from being completely transparent to being completely opaque. The different clarity levels are prized differently for the opals; for example, the crystal opal is preferred to be completely transparent, while the black opal should be completely opaque to accentuate its play-of-color. The cloudy and milky type of opal gemstone is considered low-valued by experts because it represents instability, and the colors do not show correctly on it.
The value of an opal is also affected by various types of clarity. More like other gems, opals also have fractures, pits, or other kinds of surface blemishes. There could be some fragments of the host rock in the opal, which is known as the Matrix. If the opal starts drying out, it will begin to develop crazing, a series of cracks resembling a spider web. The moisture of an opal can be lost if you keep it in direct sunlight or prolonged exposure to bright light. You can prevent the crazing by not displaying them on the windows. The cracked opal gems lose their charm and spoil their beauty and clarity.
Opal Cutting
The cutting of the opals is a very delicate process. The cutters try their best to preserve the play of color and pattern on the stone while planning the finished gem. The exceptional opal stones are not cut to standard shapes or sizes. The cutters intentionally keep them large and make them uneven while cutting to showcase their play-of-color very clearly, and even better. These stones are mainly for the custom pieces because they are one-of-a-kind gems. The commercial cuts are mostly done in standard sizes because they are used in making jewelry. The most common shape is oval, and while giving them the Opal cabochon cut, the cutters take care that the dome should be perfect; otherwise, it will affect the jewelry-making process. A dome is the ideal shape to see the most patterns on an opal from different angles.
Carat Weight
The weight of the gemstones is measured in carats. The carat weight is an essential factor in evaluating the value of the opals. Opal stones come in various sizes and weights. Although a opla stone has a very low density, even the larger stones are comfortably wearable. Approximately 90% of the opal in the world comes from Australia. The Fire of Australia Opal weighs around 5000 carats, which is 998 grams; it's a larger uncut opal. You can only find this big opal stone in a few places in the world, and one of them is South Australia. Commonly, the sizes of the opals that are used in jewelry are 6x4, 7x5, and 8x6 mm.
Conclusion
The quality factors of the opals are determined by evaluating many factors, but the main factor that plays an important role is play-of-color. In this blog, we have explored all the key aspects of assessing opals. The important thing is to make sure you receive a real opal gem. You should purchase it from a trusted brand by reading all the testimonials. There are also some ways by which you can find out the authenticity of the gemstone. You should look for the beautiful imperfections, such as inclusions, unique play-of-color, and pattern. Overall, we can say that Opal gemstones are very beautiful and unique, and they are also said to be good for your mental health and unlock the creative side of your mind. You should choose the best one for yourself.
