Tanzanite is one of the world’s most captivating gemstones, admired for its striking hues and fascinating optical effects. Found only in a small area of northern Tanzania, its rarity makes it both desirable and valuable. But beyond rarity, it is Tanzanite’s extraordinary play of colour that truly sets it apart. For buyers, understanding how this gem is graded – and what influences its appearance – is essential when selecting a jewel of lasting significance.
The Colour Spectrum of Tanzanite
Tanzanite’s colour ranges from delicate bluish-violet to deep indigo. Unlike sapphires, which tend to display a more uniform shade of blue, Tanzanite’s tones shift depending on both the angle of view and the light source. In daylight, it often appears a rich blue; under incandescent light, violet hues may dominate.
This interplay of colour gives Tanzanite a dynamic quality: no two gems look exactly the same. It is this characteristic that has helped make it one of the most sought-after jewels of the modern era.
Trichroism in Untreated Tanzanite
One of the scientific marvels of Tanzanite is its trichroism. Untreated Tanzanite naturally displays three distinct colours – blue, violet, and burgundy – depending on the direction from which it is viewed. Very few gemstones exhibit such an effect.
While this natural trichroism is remarkable, most Tanzanite undergoes heat treatment to reduce the burgundy component, leaving the more desirable vivid blues and violets.
Heat Treatment and Enhancement
Almost all Tanzanite on the market has been gently heated to enhance its colour. This process, carried out at controlled temperatures (typically between 500–700°C), eliminates brownish tones and intensifies the vivid blue and violet hues that buyers prize.
Importantly, this enhancement is permanent and stable – it does not diminish the gem’s integrity or value. In fact, heat treatment is considered standard practice, much like the treatments used for sapphires.
For buyers, what matters most is transparency: reputable jewellers will disclose whether a gem has been treated and provide certification to confirm authenticity.
Tanzanite International Grading Standards
To help buyers make informed decisions, the Tanzanite Foundation introduced grading standards that are now widely used in the trade. These are based on the gem’s colour, clarity, and cut, with colour given the highest weight.
- Exceptional (AAA): Rich, saturated blue-violet hues with outstanding brilliance.
- Fine (AA): Strong colour, slightly lighter than Exceptional.
- Good (A): Attractive, lighter blues and violets with less saturation.
- Fair (B): Paler shades with lower market value.
While these grades are not as universally standardised as the diamond 4Cs, they provide buyers with a useful framework for evaluating Tanzanite’s quality.
What Buyers Should Know
When purchasing Tanzanite, consider the following:
- Colour: The richer and more saturated the blue-violet hue, the more valuable the gem.
- Clarity: Like other fine gemstones, inclusions affect value. Eye-clean Tanzanite is preferred.
- Cut: The way a gem is cut influences how its colour is revealed. Skilled cutting can maximise pleochroism and brilliance.
- Certification: Always request a certificate from a recognised gemmological authority. This confirms both authenticity and quality.
- Trusted Source: Work with heritage jewellers who uphold ethical sourcing and transparent grading.
Prins & Prins Expertise
At Prins & Prins Diamonds, we combine decades of gemmological expertise with a commitment to transparency. Every Tanzanite in our collection is certified, ethically sourced, and carefully evaluated by our in-house specialists. Whether you are drawn to the intense indigos or the delicate violets, our team ensures that each client selects a gem of genuine quality and enduring value.
Conclusion
Tanzanite’s allure lies in more than its rarity; it is a gemstone of extraordinary beauty, defined by its unique trichroism and vivid colour spectrum. Understanding how it is graded empowers buyers to choose with confidence – ensuring that every purchase reflects both the natural splendour of the gem and the heritage of those who bring it to life.
Explore our curated collection of Tanzanite Jewellery and discover why this remarkable African treasure deserves a place in your collection.