1. Brightness is everything: if we must make the problem clear in one sentence, it is "the brighter the opal, the better the quality". Low-grade opal looks like a disgrace.
2. Present more than three colors: The top-grade opal must present multiple colors, that is, three or more colors.
3. Indispensable high saturation: Saturation is also the purity of color. When every color of an opal gem is bright and saturated, it is another excellent symbol.
4. Judging the pros and cons from the graphics: This is the unique judging feature of Opal, and different color patterns also determine the value of Opal. Because the surface color of opal is irregular corner spots or spots, it is best to have mottled corner spots. Wonderful patterns are called multicolored, ribbons, straw, chaff and so on. And some irregular patterns symbolize some beautiful things or look like a painting. Excellent patterns are very clear, including flowers, spins, lightning and flames. The poor pattern is vague, and only a few small color spots appear, such as moss and grass.
5. Large size is always dominant: no matter what kind of gem you buy, carat weight is the key factor affecting the price. The thickness of the whole opal is related to the size and shape of the opal itself, which is an important factor to be considered and calculated when measuring the value.
6. "Rotating" observation is safer: because the value of opal is completely determined by color, the more uniform the color, the higher the value. Therefore, when buying opal, we should pay attention to the overall effect of the color change of the gemstone and rotate it 360 degrees. The brightness, saturation and color of high-quality opal run through, and there is no "blind zone".
7. Be smart about semi-finished products: Opal is a very soft gem, suitable for egg surface processing or carving, and the ring surface can only be inlaid. If you happen to buy a pendant and want to punch it, it is a very risky move. Because any heating device may cause the water in the opal to evaporate, the direct result is that your opal will not only crack, but also lose its most valuable discoloration effect and become a pebble stronger than ordinary stones. To sum up, it is recommended to buy Opal finished jewelry or Opal semi-finished products that are easy to process.
8. Choose without flaws: flaws are something that no gem wants to see, and all kinds of flaws will weaken the value of Opal. Opal is of little value if there are obvious cracks on its surface. Opal with many fine cracks on its surface will also become worthless. Sometimes sand holes or other mineral impurities are found under or in colored opals. The color and pattern of high-quality opal should be continuous and change with different angles. When opal cannot produce a changing surface, the color presented from only one angle will also devalue the gem.
9. Be sure to have a certificate: In order not to waste money and pave the way for future investment, the jeweler is required to provide a certificate when buying gems. It is always an essential step to ask jewelers to produce authoritative gem appraisal certificates, not only to prove the value to insurance companies or resell them, but also to clarify the responsibilities of both parties.
The evaluation of Opal mainly depends on the following three factors.
Background color: when evaluating opal, it is generally considered that the dark background color (gray, brown, blue, black, etc. ) is better than light background color (light white, bright gray), which can better reflect the color change of Opal. High-quality black opal, its value can exceed sapphire.
Color type: On opal, the more colors, the better. In black opal and white opal, people generally like red, followed by purple, orange, yellow, green and blue. Among fire opals, purple, green and blue are the best. Because the contrast between these colors and their body colors (background colors) is stronger, they are more vivid. Especially the high-quality opal can constantly change and move when rotating, which makes people feel like they are in a dream of color.
Size and shape of the stain: In Opal, according to the color of the stain, Opal can be divided into monochrome (basically composed of 1 color), 3 colors (basically composed of 2 or 3 colors) and 5 colors (basically composed of all colors from red to purple). Like rainbows, it is generally believed that the spots are large and the colors are mostly top grade. In addition, the shape of the stain is also very important. For example, some stains are patterned (called colored opal) and some stains are flame-like (called flame opal). The value of opal with such color points is higher than that without these color points.