How can the perception of a gemstone colour differ?

Playing with perception and vision, gemstones are multifaceted delights. From glistening sapphires to bright rubies and every jewel in between, gemstones can look entirely different depending on their characteristics and the conditions they’re viewed in.

The correct term for this optical gemstone phenomenon? Photochromism. Perhaps you’ve experienced a similar optical phenomenon in the past. You’ve ordered something online and the colour doesn’t match up to the website’s image or you brought something in store and the item looked different once you tried it on at home. There was also ‘The Dress’, which took the internet by storm in 2015–the dress was in fact blue and black and was the result of overexposure and shadows.

The colour of a gemstone can also appear more vivid under one setting and paler in comparison in an opposing situation. For example, the warm tones of yellow gold can emphasise the green in a teal gemstone, making the colour appear more vividly teal.

On gemstones with a lighter tone that look more ‘pastel-ey’, we’d recommend a claw setting to allow as much light as possible to enter the stone. Due to the level of colour present in them, a gemstone with a deeper colour, such as a royal blue sapphire, would work when set with a claw or bezel setting.

The appearance and colour nuances of a gemstone change on account of the lighting, an optical phenomenon called photochromism. Sunlight, daylight, and artificial light have a significant impact on colour alteration therefore it’s important to note how the colour can vary under different settings, adding to the stone’s overall charm.

Natural daylight is deemed the most popular form of lighting when viewing gemstones as the stone’s flaws, colour and brilliance appear more prominent. It’s also important to note the light’s interaction with the stone can differ depending on the time of the day and your geographical location as viewing gemstones under direct sunlight will result in more glare.

Incandescent lighting emits warmer wavelengths which can influence the colour of gemstones. A ruby may appear pinker under incandescent light whilst a yellow sapphire will appear more enhanced in colour thanks to the light’s yellow-tinged cast. However, it’s important to keep in mind that this is a rare occurrence and only occurs in 15% of gemstones.

Below shows an oval purple sapphire rotating from direct light to shadow to display the difference in colour profiles present in the stone under each lighting condition. Notice how the deeper purple and inky blue tones appear more prevalently when in darker conditions and the more violet tones are more obvious to the eye when faced in direct light.

Paying close attention is of paramount importance when observing a gemstone and its colour on digital devices. It’s key to keep in mind how display colours can have an impact on the overall appearance of a gemstone, especially as each digital device has a specific colour profile. When viewing gemstones on screens, whether a tablet or smartphone, make sure to check the screen’s brightness levels alongside certain features such as yellow light and other colour deviations, as this can adjust the gemstone’s hue.

The varying angles of a gemstone can also modify its colour and appearance. Pleochroism is an optical phenomenon in which gemstones change in colour when viewed from different angles due to colour zoning. The crystalline structure of the stone allows the refracted light to pass through, meaning the light is then either refracted or absorbed by the stone. This can then result in an array of colour changes or subtle shifts that can alter the perception of the stone.

Branching out further into scientific terms, dichroism denotes a stone has an optical axis and shows two colours, whilst trichroism indicates the stone holds three colours due to two different axes. In layman’s terms, a dichroic stone reflects light in two different colours when examined from two different directions. A trichroic stone reflects light in three different colours when viewed from three different directions.

The ring below is a prime example of the direct impact of pleochroism. The sapphire has been captured under identical lighting conditions yet evidently changes in colour and life on account of its position and angle on the ring.

Choosing the right gemstone for your jewellery is always down to personal preference and can often boil down to a combination of several qualities. Not only is gemstone colour perception often part of the stone’s DNA, it’s also a key element of its overall charm; a stone that can appear a certain way in one environment, can have several other meanings under new lights.

At Taylor & Hart, our skilled team is dedicated to sourcing perfect gemstones and double-inspects every gemstone for symmetry, polish, and colour across the stone and the way the light interacts with the stone; all whilst ensuring the stone retains its unique appeal.

It’s often said that you don’t choose the stone, the stone chooses you and sometimes upon first glance, there’s a feeling that it’s meant to be.