Jewellery

Beyond Sapphire: Exploring the Mystique of Blue Gems

14 July 2025

Kate Jolley

There’s something undeniably captivating about the colour blue in jewellery—its depth, its elegance, its calm allure. From the regal richness of sapphires to the icy clarity of aquamarines, blue gemstones have long fascinated collectors, designers, and gem enthusiasts alike. Yet, despite their popularity, these stones often present a puzzle. What type of gem is it really? Is it natural or treated? Antique or modern? Questions like these are what keep jewellery specialists busy and why accurate identification is crucial—especially in the world of auctions, where value hinges on authenticity and provenance.

In this article, we delve into the world of blue gemstones that frequently pass through the hands of Lyon & Turnbull’s jewellery experts. We’ll explore their histories, their visual similarities, and the subtle differences that can drastically affect their value. By the end, you might look at the pieces in your own jewellery box a little differently—and perhaps be inspired to seek out a specialist to uncover the hidden stories behind your own treasures.

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The four blue gemstones that most people are familiar with are sapphire, Tanzanite, aquamarine, and blue topaz. Of these four, sapphire is perhaps the most sought after currently. Sapphires are one of the Big Three - a term that refers to the trio of coloured gemstones including rubies and emeralds that attract the highest value on the market today.

Sapphires

Sapphires are part of the corundum family, the same mineral that produces rubies. They rank just below diamonds on the Mohs hardness scale*, making them a popular and durable choice for engagement rings. One of the most famous examples is Princess Diana’s iconic sapphire engagement ring, now worn by Catherine, Princess of Wales. While we most commonly associate sapphires with the colour blue, they actually come in a stunning variety of hues, including pink, yellow, purple, and green.

However, when it comes to blue sapphires, there is a preferred tone: intense and velvety, not too dark, not too light. Jewellery designers and collectors typically look for even saturation and vibrant colour. Among blue sapphires, the benchmark to which all others are compared is the mythic Kashmir sapphire.

The Kashmir sapphire refers to stones discovered along the India/Pakistan border in the late 19th century, when a landslide revealed a small deposit of these vividly blue gems. The mine was quickly depleted, and today, authentic Kashmir sapphires are only found in antique jewellery. If you see a gem labelled ‘Kashmir-coloured,’ it simply refers to the hue resembling those legendary stones, not the origin. The real McCoy, with provenance linking it to that original mine, is exceptionally rare and highly valued.

While Kashmir sapphires are often held as the ideal, the truth is that the ‘perfect’ gem is ultimately subjective. The benefit of sapphires is their tonal diversity. They come in greyish-blue, cornflower blue, and some even have violet undertones. Because of this range in hue, it’s quite easy to mistake a blue sapphire for another gem – like Tanzanite.

Which would you choose?

Tanzanite is one such gem that closely resembles blue sapphire. In fact, one of the best ways to understand their differences is to examine them side by side.

The distinction between these two stones isn’t always obvious at first glance. But accurate identification is essential for valuation purposes.

A Sapphire and Diamond Set Ring

Sold for £13,750 incl premium

A Modern Tanzanite and Diamond Set Ring

Sold for £7,375 incl premium

Tanzanite

So what makes the difference? While they may look similar, Tanzanite and sapphire are fundamentally different gems. Tanzanite, found only in Tanzania, was introduced to the jewellery world in 1967 and named by Tiffany & Co. It remains one of the few relatively recent additions to the fine gemstone market. As such, Tanzanites are usually seen in vintage or estate jewellery, rather than antique pieces.

Tanzanite’s appeal lies in its trichroism – the ability to display three distinct colours depending on the viewing angle: blue, violet, and greenish. The gemstone cutter plays a crucial role in determining which of these hues is most prominent by orienting the facets accordingly. The most desirable Tanzanites often echo the same velvety blue found in sapphires, with hints of violet that give them a unique depth and shimmer. Some Tanzanites are cut to emphasise lavender or violet tones, creating gems that can resemble fine amethysts.

Having explored the deep blues of sapphire and Tanzanite, we now turn our attention to two lighter but equally enchanting blue gems: aquamarine and blue topaz.

Aquamarine

Aquamarine, as its name suggests (from the Latin for seawater), is typically an icy, pale blue. It has minimal inclusions and is usually very clear to the eye. This clarity makes aquamarines excellent candidates for emerald-cuts and baguette-cuts, which are styles that emphasize transparency over sparkle. Aquamarine’s subtlety makes it a favourite in Art Deco jewellery, where it often features in sleek, geometric designs.

Belonging to the beryl family – the same as emeralds and Morganites – aquamarines are sometimes mistaken for other clear-toned coloured gems, such as rose quartz or tourmaline. However, few gems rival aquamarine’s ability to combine delicate colour with exceptional clarity.

Tanzanite may have Tiffany & Co. to thank for its popularity, but aquamarine owes much of its widespread appeal to Cartier. During the aftermath of the 1929 Stock Market Crash, fine jewels made from diamonds, rubies, and emeralds became largely unaffordable. Cartier saw an opportunity and began crafting exquisite aquamarine jewellery at a more accessible price point. Their innovative designs helped aquamarine gain traction with a new generation of collectors, and by the time competitors caught on, the finest stones had already been snapped up.

Cartier: An Aquamarine and Diamond Brooch

Sold for £7,560 incl premium

Many of the best aquamarines come from Brazil, particularly from a region called Pedra Azul, where the famed Dom Pedro crystal was discovered. This enormous obelisk-shaped gem exhibits aquamarine’s tonal gradient, from pale at the base to deep and saturated at the tip, demonstrating the gem’s capacity for colour variation.

Aquamarines range from nearly colourless pale blues to medium-dark, intense blues with green undertones. This greenish tint often makes them indistinguishable from blue topaz at a glance.

Which would you choose?

An Aquamarine and Diamond Pendant

Sold for £5,040 incl premium

A Blue Topaz and Diamond Pendant

Sold for £1,008 incl premium

Blue Topaz

Blue topaz is frequently used as a substitute for aquamarine because of their similar appearance. However, it is a desirable gemstone in its own right, known for its range of vibrant blue hues. There are three main shades of blue topaz: Sky Blue (light and airy), Swiss Blue (electric and bright), and London Blue (deep and inky, with a grey undertone).

Among these, London Blue is often considered the most sophisticated due to its moody depth. Sky Blue is the most commonly mistaken for aquamarine due to their nearly identical pale blue shade. Swiss Blue offers a more vibrant, statement-worthy option ideal for contemporary cocktail rings.

Like sapphire, topaz also comes in a variety of colours, spanning the rainbow from blue to pink, yellow, and even red. It also shares with Tanzanite the ability to display different colours from different angles, depending on how it is cut.

Topaz has a rich history of use in jewellery, dating back to ancient Greece. It became particularly fashionable in the 18th and 19th centuries with the discovery of Imperial Topaz – a deep golden to reddish-orange variety – which was especially prized by Russian nobility.

Meet the Specialists

When considering the mosaic of precious gems available today, identifying them correctly can feel daunting. That’s why it’s essential to consult with a professional who can verify and value the stones you may already own.

Whether you are interested in our valuation services, are considering selling through auction, or are simply curious about your jewellery collection, we are always happy to help. You never know what treasures might be hiding in plain sight – perhaps even a gem with a story as fascinating as its sparkle.

Kate Jolley

Associate Jewellery Specialist | Edinburgh

Ruth Davis

Head of Jewellery | Edinburgh

Beyond Sapphire: Exploring the Mystique of Blue Gems

Our Jewellery Department

Sapphires

Which would you choose?

A Sapphire and Diamond Set Ring

A Modern Tanzanite and Diamond Set Ring

Tanzanite

Aquamarine

Cartier: An Aquamarine and Diamond Brooch

Which would you choose?

An Aquamarine and Diamond Pendant

A Blue Topaz and Diamond Pendant

Blue Topaz

Meet the Specialists

Kate Jolley

Ruth Davis

The Department

Jewellery