Ruby Month: the fire within

Describing colour in gemstones is a little like describing the ephemeral. We can feel it, see its effects, and experience its intensity, yet the moment we try to define it precisely, language begins to fall short.

Our eyes can distinguish millions of colour variations, far more than our vocabulary can comfortably name. In emeralds and rubies, especially, what we casually call “red” or “green” is rarely just that. A ruby may show flashes of pinkish-red, orangey-red, or purplish-red depending on the light. An emerald might lean bluish-green in one moment and reveal a warmer, slightly yellowish tone in another. The human eye perceives nuances instantly, whilst words struggle to keep up.

Gemmology attempts to bridge this gap by breaking colour down into components: hue (the basic colour), tone (how light or dark it is), and saturation (how vivid or intense it appears). This structured language helps professionals communicate more clearly. Yet even then, colour remains subjective. Two people can look at the same gem and describe it differently because perception is influenced by lighting, environment, and even personal sensitivity to colour.

A ruby’s red comes from trace elements of chromium, and how it interacts with surrounding oxygen ions, as this affects the rays of light that are absorbed or reflected within the crystal. Rubies from Mozambique display the full known spectrum of colour ranges, including the most vivid, red hue, and naturally fluoresce under UV light.

There is of course another dimension to colour in rubies, in that the gemstone possesses pleochroism – the ability to display different colours when turned at different angles due to selective absorption of light. It is the skill of the gemstone cutter to marry these colours together and form the most pleasing, vivid crimson. The beauty is, as ever, in the details, as subtle movements reveal flashes of orange, pink and purple, a dance which is referred to as the ‘fire within’, evoking a picture of glowing embers and the rawest of emotions.

This is why gemstones, and rubies in particular, are so fascinating: they resist rigid definition. Their beauty lies in subtle shifts, in the interplay between light and matter, in nuances that cannot be fully captured by simple words. The act of seeing outpaces speaking, and perhaps that mystery is part of what makes the colour in gemstones so powerful.