Identifying raw gemstones requires keen observation, knowledge of their physical properties, and familiarity with local geology. Nigeria is rich in gemstones such as tourmaline, sapphire, and aquamarine, often found in areas like Jos, Kaduna, and Taraba states. To identify these gemstones in their raw state, consider the following key factors:

Physical Properties of Gemstones
- Colour: Most gemstones have distinctive colours, though impurities can alter their appearance. For instance, tourmalines are known for their wide range of hues, while sapphires are typically blue but can also be found in other colours.
- Hardness: Use the Mohs scale of mineral hardness to test durability. Diamonds, for example, rank highest on this scale with a rating of 10, while aquamarine has a hardness of 7.5 to 8.
- Lustre: Observe how the surface reflects light. Gemstones often exhibit a shiny or glassy appearance, which helps distinguish them from ordinary rocks.
- Specific Gravity: Measure the density of the raw gemstones. Gemstones are typically heavier than ordinary rocks due to their mineral composition.
- Crystal Structure: Examine the raw gemstone’s structure. Many raw gemstones, like quartz and tourmaline, form distinct crystal shapes that can aid identification.
Key Steps for Identification
- Observation and Visual Inspection: Closely examine the gemstone using natural light or a handheld light source to identify its colour, transparency, and any visible inclusions.
- Field Testing:
- Use a hand lens or magnifying glass to observe fine details such as surface texture and crystal form.
- Test hardness using common tools or a scratch test to determine its resistance to abrasion.
- Geological Context: Familiarise yourself with areas in Nigeria where gemstones are commonly found, such as:
- Jos Plateau: Known for tin and gemstone mining, including tourmalines and sapphires.
- Kaduna State: Rich in garnet and amethyst deposits.
- Taraba State: A hotspot for aquamarine and topaz.
- Specific Gravity Testing: Use simple tools like a scale and water displacement method to calculate the gemstone’s density.
- Advanced Tools and Techniques:
- Gem Identification Guides: Books and online resources can provide detailed descriptions and photographs.
- Spectroscope: Helps identify a gemstone by analysing its light spectrum.
- Refractometer: Measures the refractive index, a key property of gemstones.
Working with Experts
Investing in tools like a hand lens and working with experienced miners can significantly enhance your ability to identify raw gemstones. Collaborating with local geologists and miners can also provide valuable insights into the unique characteristics of gemstones in different Nigerian regions.
Challenges and Tips
- Identifying Impurities: Impurities can sometimes obscure a gemstone’s true identity. Learning to recognise common inclusions can improve accuracy.
- Distinguishing Lookalikes: Many raw gemstones have similar appearances. For example, quartz can resemble topaz but differs in hardness and density.
- Building Experience: Practical experience is crucial. Regular field visits and hands-on practice improve recognition skills over time.
- Legal Considerations: Be aware of local mining regulations to ensure compliance when exploring or collecting gemstones. The Nigerian Minerals and Mining Act provides guidelines for small-scale and artisanal mining.
Gemstone identification is a rewarding skill that requires observation, patience, and practice. By understanding physical properties, leveraging tools, and learning from experts, individuals can confidently identify raw gemstones. This skill not only benefits personal exploration but also contributes to Nigeria’s growing mining.