STORIES - Sapphires, Rubies and Emeralds: The "Big Three" Coloured Gemstones

Long before diamonds became the centrepiece of engagement rings, it was colour that signified rarity and status. Among the thousands of gemstones found across the earth, three have held their position at the very top for centuries: sapphire, ruby and emerald. Together, they're known in the trade as the "Big Three." In this blog, we look at what sets each of them apart and why ruby, in particular, has long been called the king of gemstones.

What makes a gemstone one of the "Big Three"?

Sapphire, ruby and emerald share a few things that set them apart from the vast majority of coloured stones: exceptional rarity in fine quality, a long, unbroken history of royal and cultural significance, and a hardness that makes them genuinely durable for daily wear. Interestingly, sapphire and ruby are actually the same mineral (corundum) with ruby simply being the red variety and sapphire covering every other colour.

Ruby — the king of gemstones

Ruby owes its striking red colour to traces of chromium within the corundum crystal. The finest rubies, particularly those with a deep, vivid red often described as "pigeon's blood," are among the rarest and most valuable gemstones in the world — in top quality, rarer and more valuable per carat than a diamond of comparable size.

Historically, ruby has been associated with passion, protection and power. In Sanskrit, ruby was called ratnaraj, meaning "king of gemstones," a title still used today. Warriors in some ancient cultures reportedly embedded rubies into their skin, believing the stone offered protection in battle. With a hardness of 9 on the Mohs scale, second only to diamond, ruby has always been as suited to daily wear as it is symbolically loaded.

Sapphire — the stone of wisdom and loyalty

While blue is the colour most associated with sapphire, the stone actually occurs in nearly every colour except red: pink, yellow, green and even colour-changing varieties all exist, known as "fancy sapphires." The most prized remain the deep, velvety blue stones, historically sourced from regions like Kashmir, Myanmar (Burma) and Sri Lanka.

Sapphire has long been linked to wisdom, loyalty and nobility. It's perhaps most famously known today for its role in royal engagement rings, following its use in the ring later worn by Diana, Princess of Wales, and subsequently by Catherine, Princess of Wales. Sharing ruby's corundum structure, sapphire is equally hard and durable, making it a lasting choice for jewellery worn every day.

Emerald — the stone of renewal

Emerald is a variety of the mineral beryl, coloured a deep green by traces of chromium and vanadium. Its rich colour has made it a symbol of rebirth and renewal since antiquity, Cleopatra was famously known for her love of emeralds, and ancient Egyptians associated the stone with fertility and eternal youth.

Unlike ruby and sapphire, emerald almost always contains visible inclusions, often described poetically as its jardin, French for "garden." Rather than being considered a flaw, this internal characteristic is accepted as part of the stone's natural identity. Emerald is softer than ruby and sapphire, at 7.5–8 on the Mohs scale, and typically more included, which makes it slightly more delicate, a consideration when choosing a setting for daily wear.

Colour, clarity and value

As with diamonds, the Big Three are evaluated on colour, clarity, cut and carat weight, but for coloured gemstones, colour is the single most important factor in value. A vivid, evenly saturated hue, free of unwanted secondary tones, can make a smaller stone more valuable than a larger one with a duller or uneven colour.

Origin also plays a significant role in value for these three stones in particular. A Kashmir sapphire, a Burmese ruby or a Colombian emerald can command a considerable premium over a stone of similar visual quality from another source, purely because of the reputation tied to that origin.

Choosing between them

There's no hierarchy that fits everyone, each stone carries its own character. Ruby offers boldness and warmth, sapphire brings depth and versatility across an unexpected range of colours, and emerald carries a softer, more storied kind of beauty in its inclusions. Together, the Big Three remain, centuries on, the benchmark against which every other coloured gemstone is still measured.