A Jeweller’s Guide to Tanzanite: Identification Tips and Jewellery Making Advice
Welcome to the mesmerising world of tanzanite!
Beloved for its vivid violet-blue hues and fascinating optical effects, tanzanite is a relatively new gemstone on the scene, but it has already made a big impression. First discovered in the 1960s in a single location in Tanzania, this gem quickly gained popularity for its extraordinary colour and was even declared an official birthstone.
Whether you're designing refined, elegant pieces or bold modern creations, tanzanite offers a unique palette and story. Let’s explore everything a jeweller should know about this captivating gem.
Basic Identification Information
Name & Synonyms:
Tanzanite (occasionally referred to by its mineral name, zoisite, though rarely in a jewellery context)
Species:
Zoisite (variety: tanzanite)
Colour Range:
Most prized for its deep violet-blue, but can range from blue to bluish purple to violet. Lower-grade stones may appear more greyish or brownish before treatment.
Refractive Index:
1.691 – 1.700 (+ or - 0.005)
Birefringence:
0.008 – 0.013
Optical Sign:
Biaxial positive
Pleochroism:
3 Colours
deep blue, purple & green or
deep blue, purplish red & greenish yellow or
reddish purple, blue, & yellowish brown
Specific Gravity:
3.35
Fluorescence:
None
Lustre:
Vitreous
Clarity:
Type 1 (usually eye-clean)
Inclusions are relatively rare in fine-quality stones, though feathers and needles may appear in lower grades.
Gems Often Mistaken for Tanzanite:
Iolite, sapphire, spinel, and coloured glass
Mohs Hardness:
6 to 7
Wearability:
Fair to good. Best suited to pendants and earrings, or rings worn with care.
Birthstone:
December (added in 2002)
Common Treatments
Nearly all tanzanite on the market has been heat treated to enhance its violet-blue colour. This is considered standard and stable, but it’s worth disclosing to clients. Naturally vivid blue tanzanite exists but is exceptionally rare and commands a premium.
Durability Considerations
Tanzanite’s relatively low hardness and distinct cleavage make it more delicate than many mainstream gems. It can be scratched by household dust or split if knocked sharply in the wrong direction. As such care is crucial, especially for rings or bracelets.
Despite this, it’s perfectly wearable with the right setting and some mindful handling. Educating clients on gentle care will help preserve their jewellery’s beauty.
Jeweller’s Setting Tips
When setting tanzanite, it’s important to remember that while the gem is visually stunning, it also has distinct vulnerabilities. Due to its cleavage and moderate hardness, it's more prone to damage than other popular gems. Bezel settings are often the best choice for rings or other pieces likely to experience impact. Halo settings can also work well, offering both visual emphasis and additional safeguarding.
For earrings and pendants, prong settings are generally acceptable since these pieces are less likely to be knocked or scratched during wear. However, even in these cases, it’s a good idea to avoid overly fine or exposed settings.
During the setting process, care must be taken not to apply pressure to the stone’s edges or corners, as this can cause cleavage fractures.
Tanzanite is also sensitive to heat. It’s best to avoid soldering near a set stone, as rapid temperature changes or direct flame contact may lead to internal damage. In an ideal world, all high-heat work will be completed before the stone is set, but if adjustments are needed, make sure you use a heat-sink.
Care Instructions
Cleaning:
Stick with warm, soapy water and a soft brush. Avoid ultrasonic and steam cleaners—tanzanite is too fragile for those methods.
Storage:
Keep separate from harder gems like quartz, sapphire or spinel. Wrap in soft cloth or use individual compartments.
Daily Wear:
Tanzanite jewellery is best worn occasionally rather than daily. Ideal for special occasions or low-contact days.
Aesthetic & Design Insights
Tanzanite’s dynamic play of blue, purple, and violet gives it remarkable visual interest. It shines in both classic and modern designs, offering jewellers a lot of creative flexibility.
Metal Pairings:
White gold and platinum enhance its cool tones for a luxurious, elegant finish. Yellow gold can offer a striking contrast for a warmer, regal look.
Companion Stones:
Tanzanite looks stunning alongside white diamonds, pearls, moonstone, and light-coloured sapphires. Consider pairing with cool-toned gems or colourless accents to let the tanzanite shine.
Design Styles:
Perfect for romantic, ethereal designs or clean, minimalist aesthetics that allow the colour to take centre stage. Also a favourite in vintage-inspired jewellery due to its lush, velvety hues.
Market & Ethical Notes
Tanzanite is found exclusively in a small mining area near Mount Kilimanjaro in Tanzania, making it one of the most geographically limited gemstones in the world.
This rarity adds to its allure, but it also means supply is vulnerable to market fluctuations and mining restrictions. Always seek suppliers who are transparent about sourcing and give back to Tanzanian communities.
In recent years, the Tanzanian government has implemented stricter export regulations to protect the gem’s value and encourage local cutting and processing.
Symbolic & Spiritual Meanings
Despite being such a new discovery, tanzanite is often associated with transformation and spiritual growth. Its shifting colours are said to reflect intuition and inner vision, making it a popular choice for those drawn to metaphysical properties.
It’s linked with the third eye and crown chakras, believed to aid in insight, awareness, and emotional healing.
Some also see it as a stone of new beginnings, fitting, given its relatively recent discovery.
Etymology
The name Tanzanite was coined by Tiffany & Co. shortly after the gem’s discovery in 1967, highlighting its country of origin. It was originally called “blue zoisite,” but marketing concerns about it sounding like “suicide” prompted a swift rebrand.
The new name honoured its Tanzanian roots and helped launch the gem into global fame.