{"id":1940,"date":"2026-06-16T22:38:25","date_gmt":"2026-06-16T22:38:25","guid":{"rendered":"https:\/\/antoniocolonna.com\/?p=1940"},"modified":"2026-09-14T19:19:33","modified_gmt":"2026-09-14T19:19:33","slug":"alexandrite","status":"publish","type":"post","link":"https:\/\/www.antoniocolonna.com\/en\/blog\/alessandrite\/","title":{"rendered":"Alexandrite: guide to the colour-changing gemstone"},"content":{"rendered":"

\"Two<\/h2>\n

Alexandrite: guide to the colour-change gemstone for bespoke jewellery<\/h2>\n

Alexandrite is a gemstone that appears to change colour when the light changes: green or blue-green in daylight or fluorescent light, and purplish red, violet-red or brownish red in incandescent light. It is a rare, fascinating and unconventional stone, suitable for those looking for a piece of jewellery with a subtle presence that is capable of surprising.<\/p>\n

In my work, I consider it a gemstone to be chosen with great care. It isn't enough to read \u201calexandrite\u201d on a certificate: you have to observe the strength of the colour change, the quality of the two hues, the transparency, the cut and the documentation. This guide helps you understand what to look for before imagining it in a ring, a pendant or a bespoke piece of jewellery.<\/p>\n

What is alexandrite<\/h2>\n

Often described, even by GIA, as an \u201cemerald by day and ruby by night\u201d: an extremely rare variety of chrysoberyl that shifts from blue-green in daylight to red or purple in incandescent light. Its identity stems from the way it absorbs light: under different sources the stone can display very different colours, with a transition that in the finest specimens ranges from green or blue-green to purplish-red.<\/p>\n

This transformation is so recognisable that, in gemmological language, it is often referred to as the \u201calexandrite effect\u201d. However, it is important to distinguish the colour change from pleochroism. Alexandrite can display different colours when viewed from different crystal directions, but its main appeal depends above all on the gem's response to different light sources.<\/p>\n

For this reason, it should not be judged with just one lamp and in a single position. A true evaluation requires a comparison between daylight or fluorescent light and incandescent light.<\/p>\n

\"Oval
Oval alexandrite observed under two lighting conditions to highlight the colour change.<\/figcaption><\/figure>\n

Month, anniversary and symbolic value<\/h2>\n

According to GIA, alexandrite is one of the birthstones for June, alongside the pearl and moonstone, and is also associated with the fifty-fifth wedding anniversary. Because of this, it can become a very personal choice for a birthday, a milestone anniversary or a piece of jewellery that tells a story of transformation: a before and an after, one light and another, a story that changes yet remains recognisable.<\/p>\n

When a gemstone has a connection to birth, an anniversary or a family memory, I like to incorporate it into a design that is not just decorative. Alexandrite works well in narrative jewellery<\/a>, because its colour change subtly conveys the idea of transition, dual nature and continuity.<\/p>\n

Geological origin, discovery and deposits<\/h2>\n

Alexandrite was discovered in the nineteenth century in the Ural Mountains in Russia, and is linked to the name of Tsar Alexander II. The first Russian specimens have remained in gemmological memory for their quality of colour and particularly sharp colour change. Today, however, that material is rare: many stones on the market come from other areas, including Brazil, Sri Lanka and East Africa.<\/p>\n

\"Raw
Raw alexandrite crystal, useful for observing the gemstone before cutting.<\/figcaption><\/figure>\n

As often happens with rare gemstones, origin can affect the perception of value, but it must not replace the observation of the stone. A famous provenance does not automatically make a weak gem beautiful; similarly, a non-Russian alexandrite can be very interesting if it shows a sharp colour change, good saturation, transparency and the correct cut.<\/p>\n

\"Open-cast
Extraction area linked to the gemstone's provenance: origin may be relevant, but it does not replace the evaluation of quality.<\/figcaption><\/figure>\n

The first discoveries date back to the 1830s in the Urals; the name alexandrite was given in 1834 in honour of the future Alexander II. These first alexandrites were of very high quality and showed vibrant hues and dramatic colour changes. The gemstone is named after the young Alexander II, the upcoming heir to the throne. It captured people's attention as its red and green colours mirrored the national military colours of the Russian Empire.<\/p>\n

In the historical narrative of the gemstone, the link with the red and green colours of Imperial Russia often appears. It is a useful reference for understanding why alexandrite quickly acquired an almost legendary aura, but in the design of a contemporary piece of jewellery, I prefer to bring everything back to a concrete question: is this stone suited to the lighting conditions in which it will actually be worn?<\/p>\n

\"Black
Historical reference linked to the name of alexandrite and its nineteenth-century discovery. Alexander II<\/figcaption><\/figure>\n

Colour and colour change<\/h2>\n

Colour is the centrepiece of alexandrite. The most sought-after stones display a green or blue-green in daylight or fluorescent light and a red, purplish-red or violet-red in incandescent light. Quality does not depend solely on the presence of the phenomenon, but on its intensity: the sharper, more balanced and more distinct the transition, the more interesting the gemstone becomes. According to GIA, the finest stones are green or blue-green in daylight and red or purplish-red in incandescent light, with a distinct and clearly legible colour change.<\/p>\n

\"Facetted<\/figure>\n

A stone that is too light can lose its strength; one that is too dark can appear almost black and sacrifice brilliance. In the best gemstones, the colour remains vibrant in both light conditions. In the studio, when I evaluate an alexandrite, I observe it in natural light, cool light and incandescent light: it is the only way to understand whether the promise of the colour change is real or merely photographic.<\/p>\n

\"Facetted<\/figure>\n

Gemmological technical data<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Species \/ variety<\/th>\nChrysoberyl, alexandrite variety<\/td>\n<\/tr>\n
Chemical formula<\/th>\nBeAl2<\/sub>O4<\/sub><\/td>\n<\/tr>\n
Colour<\/th>\nBlue-green in daylight or fluorescent light; purplish-red or violet-red in incandescent light<\/td>\n<\/tr>\n
Main phenomenon<\/th>\nColour change according to the light source<\/td>\n<\/tr>\n
Refractive index<\/th>\nCirca 1,746\u20131,755<\/td>\n<\/tr>\n
Birefringence<\/th>\nCirca 0.008\u20130.010<\/td>\n<\/tr>\n
Specific gravity<\/th>\nCirca 3.73<\/td>\n<\/tr>\n
Mohs hardness<\/th>\n8,5<\/td>\n<\/tr>\n
Tenacity<\/th>\nExcellent<\/td>\n<\/tr>\n
Cleavage<\/th>\nThe gemstone retains good durability, with care needed regarding impacts and fractures.<\/td>\n<\/tr>\n
Stability<\/th>\nGenerally stable under normal conditions of use, provided the gemstone has no fractures or problematic fillings<\/td>\n<\/tr>\n
Anniversaries<\/th>\nBirthstone of the month of June; 55th wedding anniversary<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Quality factors: how do I evaluate an alexandrite<\/h2>\n

Colour change<\/h3>\n

It is the first factor to observe. A good alexandrite must have two recognisable colour personalities, not a simple variation in tone. The most desired transition goes from green or blue-green to red or purplish-red. If the colour only shifts towards a dull brown or an indistinct grey, the stone may remain interesting, but it will not have the same impact.<\/p>\n

Saturation and brightness<\/h3>\n

Saturation must be sufficient in both light conditions. I am not necessarily looking for the darkest stone: I am looking for a gem that remains lively. In alexandrite, a stone that is too gloomy may look important in a close-up photo, but it can lose readability once set.<\/p>\n

Transparency and inclusion<\/h3>\n

Good quality alexandrites tend to have few visible inclusions. However, some subtle, oriented inclusions can produce an additional phenomenon: cat's-eye, or chatoyance. When the colour change and the cat's-eye effect coexist distinctly, the gemstone becomes particularly rare and fascinating.<\/p>\n

\"\"<\/figure>\n

Cut<\/h3>\n

Alexandrite is often cut into mixed shapes, with a brilliant crown and a step-cut pavilion. The rarity of the material leads cutters to preserve weight, but carat saving should not sacrifice the face of the stone. A good cut must orient the gemstone to show the best colour change through the table.<\/p>\n

\"Close-up
Brownish-pink shade alexandrite.<\/figcaption><\/figure>\n

Carat weight<\/h3>\n

Many faceted alexandrites are under one carat. When size, quality of colour change and transparency increase together, the price can rise very markedly. Fine stones of significant size are particularly rare and can reach very high valuations. Because of this, rather than chasing a theoretical carat weight, I prefer to look for balance: a smaller but lively stone can be more convincing than a large but dull one.<\/p>\n

Practical tips for buying an alexandrite<\/h2>\n

The first rule is simple: do not buy a significant alexandrite by looking at it under just one light. Always ask to see it in different conditions and observe whether the colour change is distinct, pleasing and consistent across the whole stone. A gemstone that only changes colour well in photographs should be approached with caution.<\/p>\n

The second rule concerns documentation. Natural alexandrite is rare and precious; if a large, clean stone with a strong colour change has a surprisingly low price, it is necessary to check whether it is synthetic material or an imitation. For a significant purchase, an independent gemmological report is a practical safeguard, not a formality.<\/p>\n

A gemmological report for alexandrite should not be read like a commercial \u201cschool report\u201d, but as an identification tool. It can help to confirm whether the stone is natural or laboratory-grown, indicate any detectable treatments and, when possible and requested, provide an opinion on the geographical origin.<\/p>\n

Finally, do not underestimate the difficulty of creating pairs or suites. Two alexandrites may be similar in shape and carat weight, but differ in colour change, saturation and behaviour in the light. For earrings, three-stone rings or multiple compositions, the selection must be much more rigorous than for more common gemstones.<\/p>\n

When the project requires it, I include this check in the pathway of guided gemstone selection<\/a>identity, treatments, proportions and consistency with the piece of jewellery are evaluated before moving on to the setting.<\/p>\n

Treatments, synthetics and imitations<\/h2>\n

GIA includes alexandrite among the gemstones for which there are processes capable of modifying colour, apparent clarity or durability, and makes a clear distinction between treatments, synthetic gemstones and imitations. Alexandrites are generally untreated; however, they may present fractures. If a stone has undergone fracture filling, cleaning must be more cautious and limited to gentle methods, such as lukewarm water and mild soap. In any case, the presence or absence of treatments must be handled with clear documentation, especially when the value is significant.<\/p>\n

Lab-grown alexandrites exist, sometimes presented with terms like \u201ccreated\u201d or \u201claboratory-grown\u201d. They can have chemical and physical properties corresponding to the natural material, but they do not have the same geological rarity. Imitations also exist: the classic case is the so-called \u201calexandrite sapphire\u201d, often a synthetic corundum with a colour-change effect. The trade name alone is never enough.<\/p>\n

In the GIA classification, synthetic gemstones have chemical, physical and optical properties that are substantially similar to natural gemstones but are grown in a laboratory, whereas imitations \u2013 natural or artificial \u2013 merely mimic their appearance without sharing the same gemmological identity.<\/p>\n

Care and maintenance<\/h2>\n

With a Mohs hardness of 8.5 and excellent toughness, the gemstone retains good durability; with care taken regarding knocks and fractures, alexandrite is a gemstone also suitable for rings and frequently worn settings. This does not mean it is indestructible, but it makes it more reliable than many other coloured gemstones when the piece of jewellery is properly designed.<\/p>\n

For routine cleaning, lukewarm water and mild soap are always the safest choice. Ultrasound and steam can generally be used, but should be avoided if the stone has fractures, fillings or if there are doubts about its stability. In my studio, I always prefer to evaluate the mounted gemstone first: the stone may be durable, but the setting, inclusions and the history of the jewel matter just as much. These guidelines are in line with the technical profile reported by the GIA for alexandrite, which combines high hardness and excellent toughness; the gemstone retains good durability, with care needed regarding impacts and fractures, while always requiring attention to fractures and treatments.<\/p>\n

Alexandrite in bespoke jewellery<\/h2>\n

Alexandrite is a perfect gemstone for anyone wanting a piece of jewellery with an intimate surprise that is not immediately obvious. It can look understated by day and become warmer and more theatrical in the evening. In a Personalised jewellery with coloured gemstone<\/a>, this dual reading can become the heart of the project.<\/p>\n

\"Ring
Blue-green oval alexandrite ring, diamond halo and white metal setting.<\/figcaption><\/figure>\n

For a Bespoke Engagement Ring<\/a>, alexandrite can be an original and technically sensible choice, provided the stone is verified and the setting is designed with adequate protection. I can see it working well in white gold, platinum or rose gold, but the choice of metal should be made by comparing the gemstone in its two colour states: one metal might enhance the green and penalise the red, or vice versa.<\/p>\n

In pendants and earrings, alexandrite allows for lighter and more narrative designs. In a ring, however, one must balance height, protection, side presence and future maintenance. The gemstone must remain the protagonist without becoming fragile in real life.<\/p>\n

Common Errors to Avoid<\/h2>\n

Error 1: trusting only one photograph<\/h3>\n

Alexandrite changes according to the light. A single image can only tell part of the story of the stone, and sometimes the most flattering part. A comparison under different lighting conditions is always needed.<\/p>\n

Error 2: confusing colour change with a simple dark shade<\/h3>\n

A stone that turns dark is not automatically a good alexandrite. The value lies in the quality of the colour change, not in the fact that the gemstone looks generically different.<\/p>\n

Mistake 3: underestimating synthetics and imitations<\/h3>\n

The market features lab-created materials and imitations with ambiguous trade names. For an important gemstone, documentation is an integral part of the purchase.<\/p>\n

Error 4: search for the carat weight only<\/h3>\n

A large stone with a weak colour change can be less desirable than a smaller one that is intense, bright and well cut.<\/p>\n

Error 5: design the frame without looking at the two lights<\/h3>\n

Metal, side diamonds and setting proportions must work with both the green face and the purplish-red face of the gem.<\/p>\n

Alexandrite FAQ<\/h2>\n
\n

Is alexandrite a natural stone?<\/h3>\n

It can be, but there are also lab-grown alexandrites and imitations. For a valuable gemstone, it is prudent to request gemmological documentation confirming its identity, natural or synthetic origin, and any detectable treatments.<\/p>\n

What is the best colour of alexandrite?<\/h3>\n

The most sought-after combinations display green or blue-green in daylight or fluorescent light and red, purplish red or violet-red in incandescent light, with a sharp colour change and moderately strong to strong saturation.<\/p>\n

Is alexandrite suitable for an everyday ring?<\/h3>\n

Yes, it can be. It has a Mohs hardness of 8.5 and excellent toughness; the gemstone retains good durability, with care required regarding impacts and fractures, but the setting must protect the stone and the gem should be checked periodically, especially if the ring is worn every day.<\/p>\n

Is alexandrite rarer than emerald or ruby?<\/h3>\n

Fine natural alexandrite is very rare, especially in significant sizes and with a sharp colour change. Comparing rarity and value among different gemstones, however, requires [evaluating] quality, weight, colour, origin and documentation.<\/p>\n

What does \u201calexandrite sapphire\u201d mean?<\/h3>\n

Usually it indicates a corundum, often synthetic, produced or chosen to show a similar colour change effect. It is not natural alexandrite and should not be valued as such.<\/p>\n

How do you clean an alexandrite piece of jewellery?<\/h3>\n

Lukewarm water, mild soap and a soft cloth are the safest choice. Steam and ultrasound are generally possible, but should be avoided if the stone has fractures, fillings or if there are doubts about its condition.<\/p>\n<\/section>\n

Do you want to choose an alexandrite for a bespoke piece of jewellery?<\/h2>\n

If you are considering an alexandrite, the point is not just finding a rare stone: it is understanding whether that specific gem changes colour convincingly, if it is documented and if it can work well in the piece of jewellery you have in mind. I can help you compare multiple stones, read the real differences and turn the choice into a coherent design.<\/p>\n

You can also continue the route in the\u2019Gemstone Encyclopaedia<\/a>, comparing alexandrite with other coloured stones before choosing.<\/p>\n