Tanzanite is one of the most intriguing and popular blue gemstones available today. Bluish violet in hue, it belongs to the zoisite mineral group. This rare gem wasn't found until 1967; the year it was discovered in the foothills of Mount Kilimanjaro in Tanzania.
According to legends, these foothills were once set ablaze by a bolt of lightning. In the aftermath, a violetish blue crystal was found by Masai herders amidst the ashes of the scorched land. Soon this rare discovery was named tanzanite, after the country of its origin – Tanzania. This gem is only found in a deep and small area (approximately seven square kilometers in size) on the foothills of the mountain, which makes it a thousand times rarer than diamonds. The stone’s uncommonness, along with its visual charm, has attributed to its ever-increasing popularity.
Even though there are numerous folklores that surround the origin of the tanzanite, the reality behind its actual discovery continues to remain a mystery. However, geologists believe that it is unlikely that one may find tanzanites anywhere else on the earth. It is said that the events that led to its formation, around 585 million years ago, were so exceptional that the odds of it happening again are practically impossible.
Today, tanzanite is regarded as the second most sought-after blue gem, after sapphire.
It is said that the tanzanite, and the event that led to its birth, is symbolic of the gemstone’s power to convert negative energy into a positive one. Tanzanite also appears a different color when viewed from different angles, as it is pleochroic in nature. This fluidity and shifting of color is believed to facilitate a raised level of consciousness. Tanzanite is known to help improve mental strength and transform destructive thoughts into constructive ones. This rare gem is considered as the birthstone for December and also the stone for the 24th wedding anniversary.
Tanzanite, the magical gemstone, discovered in the late 1960's, is prized for the kaleidoscope of blue-violet colors it radiates. Among the Maasai tribes of Tanzania, this gem is presented to wives to celebrate the birth of a child and to bless the newborn with good luck and prosperity. The gift of tanzanite at child birth is distinctive and symbolic of new beginnings.
Hardness & Strength
Tanzanite exhibits a hardness of 6 to 7 on the Mohs scale. Despite the low rating, it can be used in all types of jewelry. However, proper precautions must be taken to avoid hard impact or rough usage. Tanzanite also exhibits perfect cleavage, which indicates the gem’s tendency to being chipped or broken if it receives a sharp blow. Additionally, sensitivity to rapid change in temperature makes the tanzanite more prone to breakage. But the setting of the jewelry, along with adequate care from the owner can drastically reduce the probability of damage.
Zoisite, the mineral group that the tanzanite belongs to, occurs naturally in an assortment of shades, including yellow, brown, blue and pink, to name a few. When crystals of transparent blue zoisite were first discovered, they garnered instant attention due to their physical similarity to sapphire. This was followed by laboratory experiments that confirmed the true identity of the gem. Subsequently, heat treatment was also administered to the naturally blue crystals, which resulted in an enhanced color. In the case of naturally brown and green zoisite crystals, the heat treatment successfully transformed their color to blue. These discoveries led to the creation of a considerable amount of blue zoisites, which were then introduced and marketed to the world as tanzanite.
This gem is normally heat treated at 600 degrees Celsius for around 30 minutes, which is very mild in comparison to what is done for other gems, such as sapphire. The subsequent change or enhancement in color is not likely to fade under standard light exposure and in the normal temperature range of the human environment. Untreated and naturally blue tanzanite is extremely sought-after and held in high regard amongst jewelry enthusiasts.
Quality & Grading
Versatile and rare, tanzanites are no longer considered a cheap alternative to sapphire. This vibrant and mystical gemstone’s limited availability has added to its appeal as an heirloom possession, making it a must-have for every discerning jewelry buyer who seeks distinction and rarity.
When it comes to judging the true worth of a tanzanite, there are several factors that are taken into consideration. They include the stone’s color, cut, clarity and carat.
Color is of crucial importance when determining the value of this gem. Tanzanites with deep and highly saturated hue are most valued. Deep blue makes it to the top of the list, followed by bluish purple and violet-blue. As the saturation level of the color decreases, so does the value of the gemstone.
Tanzanites are transparent gemstones with an attractive, vitreous luster. The zoisite crystals, from which they are formed, are considerably free from inclusions. An eye-visible inclusion on the cut and polished gemstone will hence result in a drop in the value.
A large, flawless tanzanite with no inclusions and the highest clarity grade of “eye clean” (also known as “flawless”) is considered the most valuable.
A tanzanite’s pleochroic nature gives it the appearance of having different colors when viewed from different angles. This particular property makes the cut, a critical element in determining the final and overall appearance of the gemstone. As blue is usually located on the short axis of the crystal, it is often considered more challenging to cut a large blue stone. This makes blue tanzanite rarer than its purple variety, and therefore more expensive.
Tanzanites are available in both traditional and contemporary cuts, with oval and cushion being the most common. The extremely rare, cat’s-eye tanzanite is fashioned into a cabochon (polished, but not faceted) to showcase its brilliant effect.
The finest colors are usually seen in large sized stones; however a large stone with less saturation is of a lower value.
Based on their properties, tanzanites can be further distinguished into the following categories of quality:
The gemstones in this category comprise of the top 1% of exceptionally rare tanzanites. They exhibit the “eye-clean” property, which refers to flawless brilliance. These tanzanites can be distinguished from the others with their rich, violetish blue color.
Almost 10% of all natural tanzanites available belong to this category. These gemstones are also “eye-clean” and display an intense blue color with a purplish tint.
This includes the top 33% of the available tanzanites. They are medium violet-blue in color and have slight inclusions.
Light violet blue in color, this category includes the top 75% of available tanzanites that have slight to moderate inclusions.
Jewelry adorned with tanzanite should be worn with care as the stone is softer than many gems. It showcases perfect cleavage and hence should be protected from hard blows and rough usage. Good care and maintenance will ensure that your tanzanite jewelry never loses its magnificent sparkle.
- Avoid placing your tanzanite with other gemstones. A compartmentalized jewelry box or a fabric lined box will help keep them apart, and thereby avoid any possible friction or scratches.
- As with all gems, keep your tanzanite jewelry away from acids and other chemicals.
- Use warm water, mild soap and a soft brush to clean tanzanite jewelry. You can then towel or air-dry it, but do not use a blow-dryer.
- Do not use ultrasonic cleaners as the high-frequency vibrations can damage the quality of the gem.
- Store your tanzanite jewelry away from direct sunlight and from extreme heat.