Rarer than Diamonds: 12 Secrets of Taaffeite, Earth’s Most Elusive Crystal

In 1945, Count Edward Charles Richard Taaffe stumbled upon a peculiar crystal that didn’t match any known gemstone. This chance discovery led to the identification of taaffeite, which remains one of the rarest minerals on Earth, with only around 50 known samples. 

With colors ranging from lilac to mauve crystal, it is often mistaken for spinel, and is approximately one million times rarer than a diamond.

Here are 12 things you need to know about this extraordinary crystal.

1. Taaffeite is a Beryllium Magnesium Aluminum Oxide

Taaffeite is a beryllium magnesium aluminum oxide with the chemical formula BeMg₃Al₈O₁₆. This unique composition sets it apart from other gemstones and contributes to its rarity.

2. It Was Discovered by Accident

Count Edward Charles Richard Taaffe, an Irish gemologist, discovered taaffeite by chance in 1945 while sorting through a box of spinel crystals.

He noticed that one of the stones displayed unusual double refraction, leading to the identification of a new mineral species.

3. Taaffeite Is Named after Its Discoverer

In honor of Count Taaffe’s discovery, the new mineral was named “taaffeite” by mineralogists Anderson, Payne, and Hey in 1951.

4. It’s Harder than Emerald but Softer than Sapphire

With a hardness of 8 to 8.5 on the Mohs scale, taaffeite is harder than emerald (7.5-8) but softer than sapphire (9). This places it among the more durable gemstones, suitable for use in jewelry.

5. Taaffeite Displays Pleochroism

One of the distinctive features of taaffeite is its pleochroism, (ref) meaning it appears to change color when viewed from different angles.

This optical property adds to its allure and helps gemologists identify the mineral.

6. It Comes in a Range of Colors

Taaffeite can be found in various shades, including colorless, pale purple, lavender, pink, red, and bluish-green.

The most sought-after specimens display a rich, vibrant color.

7. Most Taaffeite Comes from Sri Lanka

The majority of taaffeite samples have been discovered in the alluvial gravels of Sri Lanka, particularly in the gem-rich regions of Ratnapura and Kataragama. However, traces of the mineral have also been found in China and Tanzania.

8. The Largest Taaffeite Crystal Weighs Just over 1 Ounce

To date, the largest known taaffeite crystal weighs a mere 33.11 carats (approximately 0.146 oz). This highlights the scarcity and typically small size of the mineral.

9. Taaffeite Is Often Mistaken for Spinel

Due to their similar appearance, taaffeite is frequently mistaken for spinel, another rare gemstone. In fact, Count Taaffe’s discovery was made while examining a parcel of spinel crystals.

10. It’s One of the Most Expensive Gemstones

Given its rarity, taaffeite commands high prices in the gem market. A one-carat taaffeite can cost upwards of $2,500 per carat, making it one of the most expensive gemstones available.

11. Synthetic Taaffeite Has Been Produced

Scientists have successfully synthesized taaffeite in laboratory settings using the flux method. However, these synthetic specimens are mainly of interest to researchers and collectors, as natural taaffeite remains exceedingly rare.

12. Identifying Taaffeite Requires Expertise

Distinguishing taaffeite from similar-looking gemstones requires specialized knowledge and equipment. (ref) Gemologists use a combination of optical and physical properties, such as refractive index, birefringence, and specific gravity, to positively identify the mineral.