Home Knowledges Is All Tanzanite Heat Treated: All You Need To Know

Is All Tanzanite Heat Treated: All You Need To Know

by Madonna

Tanzanite, the captivating blue-violet gemstone that entices jewelry enthusiasts and collectors alike, has a captivating allure. Mined exclusively in Tanzania, tanzanite’s unique color and rarity make it highly sought after in the gemstone market. However, a common question in the world of tanzanite is whether all of it undergoes heat treatment. In this article, we delve into the intriguing world of tanzanite treatment, exploring the reasons behind it, the methods employed, and the implications for buyers and collectors.

The formation process of tanzanite

Tanzanite forms deep within the Earth’s crust in Tanzania’s Merelani Hills. It originates from a parent rock called graphitic gneiss, undergoing metamorphism due to intense heat and pressure. During this geological process, trace elements like vanadium and chromium enter the rock. Over millions of years, these elements imbue tanzanite with its mesmerizing blue-violet hue. Tanzanite crystals develop within the gneiss, typically as elongated prisms or columns. Unique geological conditions in this region, including proximity to Mount Kilimanjaro and past tectonic activity, contributed to tanzanite’s formation. This rare gem’s journey from the Earth’s depths to the surface is a testament to nature’s remarkable artistry.


What is Heat Treatment of Tanzanite?

Heat treatment of tanzanite is a common and widely accepted process in the gemstone industry. This treatment involves subjecting the rough tanzanite crystals to high temperatures, typically ranging from 400 to 600 degrees Celsius. The heat treatment serves to enhance the gem’s color and clarity. During this process, brown or greenish tanzanite transforms into the sought-after blue-violet hue that defines the gem. Heat treatment replicates natural geological conditions, activating the vanadium trace elements within the crystal structure, which are responsible for tanzanite’s captivating color. This widely practiced method helps maximize the gem’s aesthetic appeal and commercial value.


The Tanzanite Transformation: Why Heat Treatment Matters?

Heat treatment is a vital step in the tanzanite journey, typically occurring after extraction. This process exposes rough tanzanite crystals to temperatures between 400 to 600 degrees Celsius. Its significance lies in transforming naturally occurring brown or green tanzanite into the enchanting blue-violet color so highly prized. The treatment replicates natural geological conditions, specifically activating trace vanadium elements within the crystal structure that are responsible for tanzanite’s distinctive color. Consequently, heat treatment not only enhances the gem’s aesthetic allure but also significantly elevates its commercial value, making it a crucial and widely accepted practice in the tanzanite industry.


Enhancing Color and Clarity Through Heat Treatment

The majority of tanzanite undergoes a heat treatment process to achieve its signature blue-violet hue. The treatment involves heating the rough crystals to temperatures ranging from 400 to 600 degrees Celsius. During this process, the brown or green hues are transformed into the mesmerizing blue-violet color that tanzanite is renowned for. This change occurs due to the alteration of oxidation states in the vanadium within the crystal lattice.

See Also: Can Tanzanite Be Purple: The Spectrum of Tanzanite’s Colors

Natural vs. Heated Tanzanite: Is There a Difference?

There is a difference between natural and heated Tanzanite, primarily in how they are treated and their resulting characteristics:

1. Origin:

Natural Tanzanite: Natural Tanzanite is formed deep within the Earth’s crust through geological processes. It is mined directly from the ground in its untreated state.

Heated Tanzanite: Heated Tanzanite is natural Tanzanite that has undergone a heat treatment process to enhance its color and clarity. This treatment is done to improve the gem’s marketability.

2. Color Enhancement:

Natural Tanzanite: In its natural state, Tanzanite often has a brownish or less vibrant color. It may require heat treatment to bring out the desirable blue or violet-blue hues.

Heated Tanzanite: The heat treatment process typically involves subjecting the gemstone to high temperatures (usually around 600-700°C) to remove the brownish or greenish hues and enhance the blue or violet color. This results in a more appealing and valuable gem.

3. Clarity Enhancement:

Natural Tanzanite: Natural Tanzanite may contain inclusions or imperfections within the gem.

Heated Tanzanite: The heat treatment process can sometimes improve the gem’s clarity by reducing or eliminating certain inclusions, making the stone more visually appealing.

4. Durability:

Natural Tanzanite: Natural Tanzanite is generally considered durable and suitable for use in jewelry.

Heated Tanzanite: The heat treatment does not significantly affect the durability of the gem. It remains suitable for use in jewelry.

5. Value:

Natural Tanzanite: Natural, untreated Tanzanite is rarer and considered more valuable among collectors and gem enthusiasts.

Heated Tanzanite: Heated Tanzanite is more common and generally less valuable than untreated, natural Tanzanite. However, it is still prized for its attractive color after treatment.

It’s important to note that heat treatment is a common and widely accepted practice in the gemstone industry for enhancing the color and clarity of certain gemstones, including Tanzanite. When purchasing Tanzanite, it’s essential to ask for information about any treatments the gemstone has undergone and to buy from reputable sources that disclose such information. Both natural and heated Tanzanite can be beautiful and desirable, depending on individual preferences and the intended use.

See Also: The Worth of My Tanzanite Ring : A Comprehensive Guide

The Prevalence of Heat Treatment in Tanzanite

The following are the prevalence of heat treatments for tanzanite:

1. The Industry Standard:

It is important to acknowledge that heat treatment is the industry standard for tanzanite. In fact, it is exceptionally rare to find untreated tanzanite in the market. This is primarily due to the fact that untreated tanzanite is less commercially viable.

2. Rarity of Natural Blue Tanzanite:

Natural blue tanzanite, the color that most buyers desire, is an extreme rarity. It occurs in only a small percentage of tanzanite rough. The vast majority of tanzanite crystals start as brownish or greenish, and heat treatment is the only viable method to transform them into the brilliant blue-violet color that is universally cherished.

3. Economic Considerations:

From an economic standpoint, heat treatment significantly increases the value and market demand for tanzanite. The enhanced color and clarity achieved through heat treatment make tanzanite a more appealing and valuable gemstone.

Ethical and Transparent Practices

While heat treatment is widely accepted in the tanzanite industry, ethical and transparent practices are essential. Reputable tanzanite dealers and jewelers disclose the treatment status of the gemstones they sell. Full disclosure allows consumers to make informed decisions when purchasing tanzanite jewelry or loose stones.

Identifying Heated Tanzanite

For gemologists and experienced jewelers, identifying heat-treated tanzanite is relatively straightforward. Microscopic examination can reveal telltale signs, such as characteristic heat-induced “halo” patterns around inclusions. However, these signs may not be visible to the naked eye, making it crucial for buyers to rely on the expertise and integrity of the seller.

The Appeal of Natural Tanzanite

While heated tanzanite is widely accepted and valued, some collectors and connoisseurs place a premium on natural, untreated tanzanite. Natural tanzanite, with its unique geological history, holds a special allure for those who appreciate its rarity and untouched beauty. For these discerning buyers, finding natural tanzanite is a matter of personal preference and the thrill of owning a piece of Earth’s history.

The Rarity and Value of Untreated Tanzanite

Untreated, natural blue tanzanite is exceedingly rare. Crystals with this color occur in only a tiny fraction of tanzanite deposits. Consequently, natural blue tanzanite commands a premium price in the market.

Untreated tanzanite is often considered a collector’s gem. Its rarity and uniqueness make it a valuable addition to any gemstone collection.

Conclusion: The Tanzanite Dilemma

In conclusion, heat treatment is a common and accepted practice in the tanzanite industry, transforming brown or green tanzanite into the dazzling blue-violet gem that captivates jewelry enthusiasts worldwide. While heated tanzanite is considered natural by gemological standards, the rarity and appeal of natural, untreated tanzanite cannot be overstated.

As the tanzanite industry continues to evolve, ethical and sustainable practices are becoming increasingly important. With responsible mining and transparent sourcing, the allure of tanzanite can coexist with a commitment to environmental and social responsibility, ensuring that this remarkable gemstone continues to shine brightly in the world of fine jewelry and gemstone collecting.


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