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How to Identify Opaque Gemstones

Opaque gemstones include a wide variety of samples from pearls and opals to turquoise and lapis. Training and experience will greatly benefit the gemstone identification process, but novices can follow several sorting steps to narrow down their identities. You'll need to make key observations of several gemstone features in order to make an educated assessment of what they are. Rely on opinions from the experts for the challenging ones. Even a trained eye may be no match for the final truth that is revealed by specialized equipment.

Instructions

- 1
  Note the color and general appearance of the stones. Most opaque gemstones have a limited range of colors that will aid in their identity. For instance, obsidian is limited to black, or black and white for snowflake varieties.
- 2
  Check out the size and shape of opaque gemstones. Pearls are readily distinguished by their rounded shapes and somewhat limited size range. Quartz varieties tend to be distributed as massive samples.
- 3
  Look at the textures of the stones. Uncut opaque gemstones such as turquoise, typically have irregular surfaces. Striations and vesicles within gemstones can be distinguishing characteristics.
- 4
  Gaze at the shine or luster on gemstone surfaces. High grade pearls and opals have highly lustrous appearances, while low-grade counterparts commonly are dull.
- 5
  Examine the gemstones to find designs and patterns on or just below the surface. Look for unique markings that can reveal their identity. For example, Tiger's eye quartz has a characteristic sheen that is evident in direct light. Opals display varying degrees of opalescent configurations on the surface and within the stones.
- 6
  Shine direct light onto the gemstone surface to see if it appears opalescent. This is a quality that will reflect light and appear almost 3-D.
- 7
  Corroborate your findings and guesses with a gemstone manual or book, such as "Gemstones of the World" by Walter Schumann. Look at pictures that are similar to your gemstones and read the accompanying material to confirm a match.
- 8
  Confirm the identity of opaque gemstones with a reputable gem or jewelry dealer. Ask them to perform testing, such as refractive index tests, to identify your gemstone samples. According to Tammy Jones, an expert pearl grader, the refractive index, or RI, will verify the true identity of gemstones.

Gemology