Differences Between Natural and Lab Grown Alexandrite

Alexandrite is among the rarest gemstones in the world. The colour-changing gemstone variant in the chrysoberyl family of crystals is valued for its ability to shift from one particular hue to another, depending on the lighting conditions the stone is subjected to. The colour of authentic alexandrite gems with good colour changing capabilities is able to shift from a variant of hue green when viewed under sunlight or fluorescent light, to a variant of raspberry red when viewed under incandescent light. Owing to their distinct colour changing feature, along with the high durability of the stone, makes them a solid gemstone for fine jewellery. Whilst the market for alexandrite gems today is driven primarily by gem enthusiasts, high-end jewellery buyers, and top jewellery companies that seek to showcase these rare gemstones in their collections. The growing demand for coloured gemstones in general, along with the appeal of more ethical and environmentally friendly gemstone options have also contributed to their growing popularity. In this post we will outline the main feature of both types of alexandrite gems: the natural and the synthetic and analyze their strengths.

Natural Alexandrite Gemstones

Alexandrite is a coloured gemstone variant in the chrysoberyl family of minerals. Chrysoberyl is a beryllium-aluminium oxide (BeAl2O4) as the result of a pegmatite process: where water separates from hardened magma over time. The Earth’s crust produces magma, which then rises to the surface due to volcanic activity, and in time cools. During this process of cooling the is enriched by H2O which brings in other rare elements, that could not enter the mineral during the process of crystallization. This combined interaction between magma, water, and the entry of an array of minerals that occur naturally gives rise to a variety of crystal types: the popular ones include those like beryllium and lithium. With respect to alexandrite gem, which is a form of beryllium, but technically it isn't, as beryllium-based minerals, like emeralds are a silicate.

What sets alexandrite gems apart from common chrysoberyl stones is the presence of chromium and in some cases vanadium; which in nature is a very rare combination, and it is this feature that is responsible for the gem’s colour. In case you have not read our introductory post on this gemstone, alexandrite in nature is very rare, and is only sourced from a handful of countries around the world. With gem quality gemstones that are able to produce the colour change effect, also known as the ‘alexandrite effect’ are even rarer. Owing to this state in the gemstone world, and with the growing demand for coloured gemstones, they can change colour under different lighting conditions increasing. Into this mix enters artificial or lab-grown alexandrite gems.

Features of Lab-Grown Alexandrite Gemstones

Lab-grown or synthetic alexandrites entered development during the 1970s, led by a company named Creative Crystals. Alexandrite gems are mainly manufactured via hydrothermal methods. Once the synthetic alexandrite gemstones are made, they are virtually identical to actual ones. However, it is important that potential buyers do their research when it comes to lab-grown alexandrites, for a considerable period of time, synthetic sapphires and other man-made gemstone variants were modified with notable trace elements like vanadium to produce a manufactured colour change effect. However, these are not genuine stones, as authentic synthetic alexandrites feature the identical chemical structure of natural stones: Al2BeO4. So customers must be aware of corundum and even spinel based fake alexandrite gems. Next, we will look at two popular alexandrite gemstone manufacturing techniques.

Flux vs Pulled Synthetic Alexandrite

If one is looking at the development process, there are two types of alexandrite stones. One of the most popular alexandrite manufacturing methods is the Czoralski or pulled method. Which was developed in the manufacture of rubies, this process was then adopted into the making of alexandrite gems. Alexandrite stones which are produced via this method, that involved seed crystals, are not considered the most authentic, as they tend to feature attributes which are not found in natural alexandrite stones, such as featuring curious striations, and the colour change effect does not always correspond to authentic stones, and stone manufactured via this methods also feature weird inclusions which are not found in natural gemstones; with this variant could be considered an alexandrite stimulant than a real alternative. However their capacity to mimic quite closely the physical properties found in a natural alexandrite stone, in addition to the notable absence of inclusions, sets these stones apart from others.

Flux alexandrite gems are artificially grown via the flux-melt process, which is also known as Flame Fusion or Verneuil process, that is commonly adopted in the world of other gemstones like sapphires: this process involves using powered chemicals that correspond to the mineral character of the gemstone type in question, which is then passed through high thermal conditions, which literally melts and then hardens into its final crystal form. Alexandrite made with the flux method on the downside tends to feature a higher number of inclusions, however, innovation came in the form of the Russian flux methods in the early 1980s, which is now the standard for this process.

One of the challenges when it comes to synthetic alexandrite stones is that they are harder to manufacture in contrast to other lab-grown gemstones, as they require the same mineral combination found in natural gemstones, in addition to the key trace minerals like chromium, vanadium that are added artificially. However, lab-grown or synthetic alexandrite gems on average tend to be of higher quality when you control for key gemstone quality factors: such as the gemstone’s clarity, the colour, and the character of the colour change effect.

What is Driving the Demand for Synthetic Alexandrite Gemstones

Alexandrite first came to global prominence following its discovery and popularization during the 19th century, following its discovery in the Ural Mountains of Russia, it soon become evident that the gemstones of this type in nature are extremely rare, but that rather than lessening its appeal only strengthened it. For in addition to the relative rarity of the rare mineral combination that gives to this colour change gemstone, the quality of the colour effect that is found in alexandrite gems also varies from stone to stone. True gem-quality stones that can exhibit or at least come close to exhibiting its characteristic ‘emerald by day, ruby by night’ feature, are even rarer. So rarity of quality alexandrite stone that can feature the ‘alexandrite effect’ prominently is a major factor.

On a more stylistic level, which is also related to the last point, is that alexandrite gems are being sought after as colour-changing side stones, that are used in fine jewellery like top necklaces and engagement rings, to supplement the main gemstone, which usually takes the form of sapphire, ruby or diamond. So the demand for new alexandrite gems has grown further, and customer preferences are such that the adoption of synthetic alexandrite as a side or accent stone is more acceptable.

Competition from Other Color Change Gemstones

It might be interesting to note that the colour change effect is not unique to the world of alexandrites. Other top gemstone variants like sapphires, spinels and even certain rare diamond types are able to feature some kind of shift in the gem’s tone or hue. Whilst the exact character of this colour changes, and the science behind it: which corresponds to the mineral character, the physical structure, and how it interacts with light varies with those that are found in alexandrite gems, the point remains that there is a competitive market for colour change gemstones. So when it comes to alexandrite stones, which despite featuring the most prominent colour change effect, their relative rarity adversely affects the supply side of the equation. Thus even if there is high demand for quality color gemstones, jewelers around the world are challenged in this regard. And here lab-grown alexandrite gems enter the mix. To meet the current demand for natural alexandrite gemstones, and also to provide an authentic alexandrite synthetic alternative to fake alexandrite stones and simulants.

Should you choose a Natural or Lab Grown Alexandrite Stone?

The answer to this question comes down to a number of factors. The price a person is willing to pay for a top-quality colour change gemstone is no doubt the most important factor. For there are gemstone sellers, and jewellers, including smaller fine jewellery companies that can provide top quality natural alexandrite stone for the right price. For example, alexandrite engagement rings that feature a natural gemstone are generally sought after. However when it comes to buying an alexandrite other factors also play a part like a gemstone's cost, the cost to gemstone quality ratio, sentimental value (as some customers tend to prefer natural gemstones) and environmental concerns. When it comes balancing cost, colour, and cut Ceylon Alexandrite gemstones have begun to make a mark: in addition to being natural gemstones, they are sourced from some of the most environmental regions in the world for gem mining. However, some customers would still prefer synthetic variants, whilst others are willing to shop around till they find the perfect natural alexandrite gemstone.