Untreated Alexandrites From Bolivia: 1960S Natural Wonder

Bolivia is a landlocked country in South America, with a rich history of mining and political upheaval. The country has experienced various military dictatorships and periods of instability, including the rule of Colonel Hugo Banzer Suárez, who came to power in a coup in 1971 and was known for his repression of left-wing and socialist opposition parties.

In the 1960s, Bolivia was ruled by a succession of leaders, including Víctor Paz Estenssoro, who was overthrown in a military coup in 1964, and Vice-President Rene Barrientos, who met a suspicious end in a helicopter crash in 1969. The political instability of this period, coupled with the country's mining history, sets the backdrop for investigating whether Alexandrites from Bolivia in the 1960s were untreated.

Alexandrite is a rare gemstone known for its colour-changing properties, first discovered in Russia in 1830. While it has since been found in other regions, including Brazil, which is now considered the main source of gem-quality Alexandrites, the discussion of Alexandrites in Bolivia during the 1960s is intriguing.

The political and social climate of Bolivia in the 1960s, with its history of mining and the power struggles between various factions, could provide a unique context for examining the treatment or lack thereof of Alexandrites from this region during that time.

Alexandrite's unique colour-changing properties

The unique colour-changing properties of alexandrite have captivated gemstone enthusiasts for centuries. This rare gemstone exhibits a chameleon-like ability to shift hues from greenish-blue to purple-red, depending on the lighting conditions. The science behind this enchanting phenomenon lies in the interplay between alexandrite's internal features and the surrounding light.

At the heart of alexandrite's colour-changing abilities are its unique light-absorbing properties. The gemstone selectively absorbs light of specific wavelengths, resulting in a transformation from a green or blue-green hue in daylight to a captivating purplish-red or ruby red under incandescent light. This effect is intensified or diminished by the cut of the stone, which affects its absorption properties.

Chromium impurities within the chemical composition of alexandrite play a pivotal role in this colour change. Chromium ions replace a portion of the aluminium ions in the stone's structure, and even a minuscule presence of less than 1% of chromium ions is sufficient to trigger this distinctive colour shift. These chromium ions strongly absorb light in the dark blue and yellow regions of the visible light spectrum, leading to the observed colour change.

The phenomenon is further influenced by external factors, particularly different light sources. Natural daylight, incandescent light, and ultraviolet light interact uniquely with alexandrite, revealing its diverse palette. Under natural daylight or fluorescent light, alexandrite showcases its pleochroic colour of green. However, when exposed to ultraviolet light, the stone displays an intense, glowing red colour due to the absorption and release of energy by chromium ions.

The vibrancy and intensity of the colour change in alexandrite are key factors in determining its value. A pronounced and vivid transformation, especially in alexandrite from the Ural Mountains in Russia, is highly prized. The saturation of the colours and the distinctness of the shift elevate the gemstone's status, making it a coveted treasure for collectors and connoisseurs alike.

The colour-changing properties of alexandrite are so remarkable that they have been given their own name—the 'Alexandrite Effect'. This effect is not merely a chemical reaction to changing light conditions but is also influenced by how our eyes adjust to different luminescence. The human visual system's colour constancy further contributes to the uniform perception of alexandrite's colours by all observers.

Alexandrite's colour-changing abilities are not limited to natural stones. Lab-created alexandrites also exhibit this property, although gemstone experts can discern a difference in the way the colour change occurs compared to natural alexandrites. The composition of natural and lab-created alexandrites may be the same, but the colour transition in natural alexandrites, formed over millions of years, holds a distinct and indescribable quality.

The rarity and enchanting colour-changing properties of alexandrite have made it a highly sought-after gemstone in jewellery. Its ability to shift from green to red elevates the beauty and allure of jewellery pieces, captivating wearers and onlookers alike. Alexandrite's symbolism of a zest for adventure, luck, and personal growth further adds to its desirability.

Alexandrite's rarity and value

Alexandrite is a semi-precious gemstone and a variety of chrysoberyl. It is known for its rarity and its ability to change colour—from emerald green in daylight to ruby red in incandescent light. It is one of the rarest gemstones and is rarer than diamond, sapphire, emerald and ruby.

Alexandrite was first discovered in the 1830s in the Ural Mountains of Russia. It requires both beryllium and chromium to form, and these two elements rarely occur in the same rocks or geological conditions. The original source of alexandrites was almost exhausted within a few decades of mining. While new sources have emerged since the 1980s, alexandrite remains one of the rarest gemstones.

The value of alexandrite is determined by factors such as where it was mined, its size, and its clarity. The two most important factors for alexandrite price are the colour quality and the intensity of its colour change, given as a percentage. Carat weight is another huge factor.

Retail prices for faceted 1-carat alexandrite often range from $500 to $20,000 per carat. The highest-quality gemstones under 1 carat can be over $22,000 per carat.

Alexandrite is too rare to have industrial uses, but its stunning appearance and excellent wearability make it a popular choice for jewellery.

Alexandrite's discovery in Russia

Alexandrite was discovered in Russia in 1830 in the Ural Mountains. The gemstone was named after the 12th birthday of the Russian Crown Prince, Alexander II, who would later become Czar Alexander II. The gemstone's colour-changing properties were seen as magical, shifting from deep forest green in sunlight to a deep merlot red under incandescent or candle light. These colours were symbolic to the Russian soldiers, as their uniforms bore the same colours. The gemstone was also believed to enable the wearer to foresee danger.

Alexandrite is considered extremely rare, with only around 1,200 carats mined in 2010, compared to 75 million carats of diamonds. The original stones from Russia were of excellent quality, with a distinct colour change from green to purple-red. However, significant finds in Russia have not been made for decades, and the small amounts that are still found contain many inclusions and are generally not considered gem-quality material.

The discovery of Alexandrite in Russia is credited to several individuals, including Yakov Vasilevich Kokovin, the Russian Ural Mountain Mine Manager around the 1800s. Finnish mineralogist Nils Gustaf Nordenskjold is also credited with finding the first samples of Alexandrite material in Russian emerald mines and suggesting the name "Alexandrite". Other contributors to the discovery include Gustav Rose, a German professor of minerology, and Count L.A. Perovskii, who submitted four mineral samples from a Uralian emerald mine for investigation.

Alexandrite's discovery in Brazil

Alexandrite is a variety of chrysoberyl, a mineral that is chemically known as beryllium aluminate (BeAl2O4). It is a gemstone that is known for its distinct colour-changing effect, shifting from green-blue to purple-red hues in daylight and incandescent light.

Alexandrite was first discovered in Russia between 1829 and 1833 when miners were digging for emeralds in the Ural Mountains. The gemstone was named after Czar Alexander II and became a national symbol for Russia. However, the harsh winters and challenging terrain of the Ural Mountains made local mining difficult. By the beginning of the 20th century, most of the Russian alexandrite had already been mined, and the fall of the Soviet Union further hindered production.

In 1987, a significant deposit of alexandrite was discovered in Lavra de Hematita, Brazil, changing the game for Brazilian alexandrite mining. The area between the Americana and Santana Valleys had produced 95% of the Minas Gerais chrysoberyl, a variety of chrysoberyl known for its cat-eye phenomena, due to the pegmatite-rich land. The Malacacheta region of Minas Gerais had also been producing alexandrite from 1975 to 1988.

Today, Brazil is the source of most of the world's alexandrite supply. Brazilian alexandrite is known for its larger carat sizes and clearer appearance compared to Russian alexandrite. It is also more likely to have metal sulfide inclusions, cloud-like fragments, and fluorite and mica crystals. In contrast, Russian alexandrite often contains phlogopite mica inclusions, tourmaline crystals, and graphite film.

Alexandrite's other sources and their characteristics

Alexandrite is a rare variety of the mineral chrysoberyl, which is composed of beryllium, aluminium, and oxygen. Its distinctive colour-changing property is caused by the presence of chromium. Alexandrite typically appears green in daylight or fluorescent light, and purplish-red in candlelight or incandescent light. However, it can also exhibit yellowish or pinkish hues. The colour-changing phenomenon is known as the "alexandrite effect".

Alexandrite was first discovered in the Ural Mountains of Russia in the 1830s by Finnish mineralogist Nils Gustaf Nordenskiöld. It was named after Czar Alexander II of Russia. While the Ural Mountains were the primary source of natural alexandrite for a long time, today, alexandrite can also be found in Brazil, Sri Lanka, Tanzania, India, Madagascar, Myanmar, and Zimbabwe.

Brazilian alexandrites tend to have pale colours, while Sri Lankan alexandrites exhibit a khaki to brown colour range. Zimbabwean alexandrites usually display little colour change and come in darker colours with purple tints. Tanzanian specimens tend to be lighter in tone, and Brazilian alexandrite is known for its blue-to-purplish colour change. The most valuable alexandrites are those with pure hues and a strong colour-changing effect.

Alexandrite is an eye-clean gemstone, meaning it contains few inclusions. It has a hardness of 8.5 on the Mohs scale, making it a durable stone suitable for daily wear and resistant to scratches and abrasions. To clean alexandrite, it is recommended to use mild soap and warm water with a soft brush.

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