Alexandrite vs Amethyst: What Are They, And What's The Difference?

In this article, you’ll learn more about these two popular stones, as well as some clues to telling them apart.

Alexandrite vs Amethyst (EXPLAINED)

Introduction

Alexandrite and Amethyst are both beautiful, sort-after gemstones that have several similar qualities that lead to people becoming confused as to which is which.

You can tell the two gemstones apart by taking careful note of their color.

Amethyst is a purple crystal with a red secondary hue, whilst Alexandrite is green in natural light but in the light of a candle or lamp, it becomes red with a hint of purple.

Added to that, both have a vitreous luster or a glassy look.

Named for the Russian tzar, Alexandrite is often referred to as an emerald by day and a ruby by night.

This is due to its unusual color change when viewed under different lighting conditions.

Amethyst does not change color like this and remains the same no matter the light to which it is exposed.

Amethyst

Amethyst is a purple-hued crystal that sometimes has a touch of blue in it.

It has a secondary red hue, leading to it occasionally being confused with other gemstones.

The purple or violet color is due to the irradiation of iron within the crystal.

It has a hardness of 7 on the Moh scale.

This makes it a fairly hard gemstone that gives off a vitreous, glassy luster, adding to its popularity, especially in jewelry making.

Amethysts are the most popular purple gem and are very affordable due to their abundance worldwide.

The largest deposits of amethyst are found in Siberia, Sri Lanka, Brazil, Uruguay, and the far east.

Smaller quantities are found in many places around the globe.

The largest deposit of amethyst, and one where the quality rivals that of the Deep Siberian deposit, is found in Brazil.

Often, deposits of several tons are found within igneous rocks.

To locate amethysts, miners will investigate the cavities within basalt flows where the deposits are located in the fractures of igneous, sedimentary, and metamorphic rock.

The highest quality amethyst is usually found in igneous rock, which is formed from lava which spreads across a wide area.

Once this basalt flow has cooled, it is referred to as volcanic rock and it is inside this that the amethyst forms.

Though the quality of amethyst found in sedimentary rocks formed from layers of sand, silt, dead plants and skeletal remains are very close, they are considered slightly inferior to those found in igneous rock.

You can also find amethyst in the cavities of metamorphic rocks.

These are formed from various different rocks that have been changed due to heat and pressure within the earth.

Small cavities called geodes can be opened in a way that shows amethyst in its natural form. These geodes are usually put on display by mounting them on a metal stand.

The most sort after and ideal grade is found in Siberia. Called Deep Siberian, the deep purple color has flashes of red or blue.

Humans have made use of amethysts for more than 2000 years.

Primarily, they have been used in jewelry and believed to have metaphysical qualities such as healing.

Though there is no scientific proof to back this up, many people persist with these beliefs.

Alexandrite

Alexandrite is a chrysoberyl that belongs to the oxide classification of minerals.

It is composed of a combination of beryllium, chromium, and aluminum oxide.

Its blue-green color comes from chromium.

Alexandrite is formed when large amounts of beryllium are found in cooling magma.

A chemical reaction with chromium, if it is present, takes place as the rock cools, forming a specific type of chrysoberyl.

Alexandrite is an extremely rare mineral and a fairly new discovery for our civilization.

Discovered recently in 1830, whilst emeralds were being mined in the Ural Mountains in Russia, it was initially assumed to be an emerald due to its green color.

However, once the Alexandrite had been looked at around the campfire, where it had turned red, the miners realized that they had stumbled on something new.

In the morning, it appeared green again.

It was from then on described as “emerald by day, ruby by night” due to its color-changing appearance.

Alexandrite was given its name due to its discovery on the birthday of Prince Alexander the Second of Russia.

Most of the Russian Alexandrite had been mined out by the end of the 19th century.

It has since been found in smaller deposits in Brazil and Zimbabwe amongst a few other locations.

Unfortunately, these gems are not of the same quality as the Russian ones but come pretty close.

The original Russian Alexandrite is much more expensive than diamonds, partly due to its scarcity, but also its beauty and color-changing ability.

It is an 8.5 on the Mohs hardness scale compared to the amethyst, which is a 7.

To put this into perspective, a diamond sits at 10.

Alexandrite also has a vitreous luster, making it glassy and clear.

Similarities

Both Alexandrite and amethyst are formed in cooling volcanic rock.

They are both mined in similar conditions and geological locations.

Though Alexandrite changes its color completely under unnatural light, an amethyst can have a slight red hue, which at night may appear to be Alexandrite at a quick glance.

They both have the same luster and, when used to make jewelry, can be cut into similarly shaped stones.

Differences

The two stones have very different chemical structures.

Amethyst is made up of a lattice of silica tetrahedra, whilst Alexandrite is made up of various metals or metal oxides.

Furthermore, Amethyst is a crystal, whilst Alexandrite is a mineral.

Amethyst is far more common than Alexandrite and is mined in large amounts across the globe.

Alexandrite is now very rare, and finding high-quality Alexandrite is even rarer still.

Because of this, amethyst is affordable to everyone, but Alexandrite is far more costly than diamonds.

If you want to purchase Alexandrite, the original Russian Alexandrite fetches astronomical prices far beyond the reach of an average person’s budget.

Why People Confuse the Two Stones

Once amethyst and Alexandrite are cut into “gemstones” for the jewelry trade, they can sometimes look similar.

In the right light, they often appear to be a similar color.

When synthetic Alexandrite is manufactured, it becomes even more confusing as the purple to red coloring becomes even closer to amethyst.

They are often mined or sourced in the same countries, leading to further confusion.

The purest examples of both stones are found in Russia.