Jewellery

A Kaleidoscope of Gemstones at Auction

15 September 2026

Hannah Murphy

Every jewellery auction we curate showcases gemstones and jewels of a rich variety, covering a breath of species and varieties, of varying origins (both geologically and geographically) and with an interesting divergence of provenances, having travelled very disparate paths to lead them to take their spot together under the bright lights (of the jewellery display cabinets!)

Many antique pieces within each auction have graced many a finger, been the belle of more than one ball, while some contemporary pieces may be yet to take their first spin.

Regardless of their deviating recent histories, most gemstones going under the hammer have an origin tale in common that dates back millions of years. Formed deep within the earth’s core, gemstones are the result of an array of chemical reactions within conditions of varying pressure and temperature.

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Pressure makes diamonds

Diamonds are perhaps the most famous example, with precise geological conditions transforming carbon (C) into the diamond crystals we know and love, rather than graphite, which is incredibly composed of the exact same chemical element.

Diamond crystals form deep inside Earth’s mantle, usually around 150–200 km below the surface, where temperatures are about 900–1,300°C and pressures are extremely high. The carbon atoms within each diamond’s crystal structure are strongly bonded, resulting in the unique strength of diamonds. Natural diamonds can take millions to billions of years to form and are brought to the earth’s surface by magma rising to the earth’s surface, with volcanic eruptions leading to the discovery of diamonds within kimberlite or lamproite rocks.

A naturally occurring subterranean science

Hundreds of natural gemstones are known to man, with each formed by a naturally occurring subterranean science which sees geological conditions and chemical elements bring to being a gemstone which is defined by the components of its creation. These gemstones can be recognised by their chemical composition and structure, their durability, colour and other defining optical features.

For example, where diamond is composed of pure carbon, ruby and sapphire are varieties of the mineral Corundum and are composed of aluminium oxide (Al₂O₃). Trace elements are responsible for the colour varieties our eyes distinguish, with the rich red colour of ruby caused by the presence of chromium. Other shades of Corundum are known as sapphire, with the best-known bearing a beautiful blue hue caused by iron and titanium.

A showcase of nature’s talents

Of the hundreds of gemstone varieties known, only around 50 of these gemstone species and varieties are typically chosen for use within jewellery.

The mindboggling array of variety of jewels which we have the honour of offering for sale is one of the inimitable benefits of buying at auction, and incredibly, the vast majority of these gemstones can be found within the pages of our Jewellery Auction catalogue, with a rich and varied array of colours, geographical origins and optical effects represented, from familiar classics to more unusual stones.

Here, we take you through just a few of the more obscure gemstones to feature in recent sales...

Alexandrite

Alexandrite is recognised as one of the world’s most captivating gemstones, prized for its extraordinary colour-change phenomenon. This colour-change variety of the mineral chrysoberyl was first discovered in the Ural Mountains of Russia in the 1830s and quickly became synonymous with Russian imperial elegance. Today, exceptional gemstone material can also be found in Sri Lanka, East Africa and Brazil.

In daylight, alexandrite typically appears green to bluish-green, while under incandescent or warm artificial light it can shift to red, purplish-red or raspberry tones. This dramatic transformation, caused by the gem’s unique optical properties and chromium content, makes fine alexandrite exceptionally rare and coveted.

Some stones may also display chatoyancy, a captivating cat’s-eye effect caused by internal inclusions. This dramatic interplay of colour and light, driven by alexandrite’s chromium content and optical properties, makes fine material exceptionally rare and coveted.

Kunzite

Kunzite is the pink to violet gem variety of spodumene, a lithium aluminium silicate valued for its refined colour, clarity and pronounced pleochroism, the optical phenomenon in which a gemstone displays different colours or intensities of colour when viewed from different directions.

First identified in California in 1902 and named after the renowned gemmologist George Frederick Kunz, Kunzite it is now sourced from notable deposits in Brazil, Afghanistan, Madagascar and Pakistan. Its colour ranges from delicate pink to lilac and violet, and the tendency of the material to form large, well-developed crystals allows for impressive faceted stones.

Amongst the most celebrated of Kunzite jewels is the impressive 396.3-carat Picasso Kunzite Necklace, designed by Paloma Picasso for Tiffany & Co. in 1986 and now held by the Smithsonian. Another is the Van Cleef & Arpels “Triphanes” suite of kunzite, amethyst and diamonds from Elizabeth Taylor’s collection, given to her by Richard Burton as an anniversary gift and sold as part of the landmark Elizabeth Taylor Collection auction in New York in December 2011.

Prasiolite

Prasiolite, or green quartz, is a rare variety of quartz distinguished by its subtle mint-green to yellow-green hues.

Whilst prasiolite does occur in nature, the green colour of prasiolite is commonly produced when amethyst or other quartz undergoes heat treatment to induce green colouration, with many of the green quartz stones on the market the result of heat or irradiation treatment of amethyst. Prasiolite is sometimes marketed as “green amethyst”, but this is a misleading trade name: amethyst is the purple variety of quartz, while prasiolite is the recognised name for green quartz.

Natural prasiolite is rare, although mines have historically been found in Poland, Canada and Namibia, with the most significant natural source in Minas Gerais, Brazil.

Spinel

Despite its remarkable history and gemmological credentials, spinel remains relatively unknown beyond the world of fine jewellery. Long overshadowed by ruby and sapphire - and historically mistaken for both - it has never enjoyed the same public recognition or commercial prominence.

Spinel exists in a wide range of colours, with a palette spanning vivid red and pink to cobalt blue, violet and deep black, with colour shaped by trace elements within its crystal structure.

The relative obscurity of spinel perhaps misrepresents the role of the gemstone in gemmological history. More than one famous ‘ruby’ has been historically misidentified as the gemstone, and most famously, the celebrated 170ct Black Prince’s Ruby in the British Imperial State Crown, which is in fact a glorious red spinel.

Black opal

Precious opal is the name given to opal which exhibits play-of-colour, the mesmerising flashes of colours caused by the diffraction of light through the unique, orderly internal structure of the opal.

Fire opal

Fire opal is a variety of opal characterised by its fiery orange-red colour. Mexico is one particularly significant source of fire opals, with the gemstone reportedly treasured by the Aztecs and Mayans.

Quite unlike precious opals, fire opals are often transparent to translucent, and are traditionally fashioned with polished facets to showcase their beauty.

Specialist

Hannah Murphy

Specialist, Jewellery & Watches | Edinburgh

Department