Opal yellow gold pendant

October Birthstone, The Beautiful Rainbow Colours of Opal

With their fascinating history and exquisite array of rainbow hues, opal gemstones are some of nature’s most miraculous and colourful treasures. Here, we consider what makes them so desirable…

5th August 2019 Ernest Jones - Editor

Opals are captivating and mysterious gemstones that many expert gemmologists spend their lives devoted to. Throughout history, October’s birthstone has been both the darling of gemstones and a bad luck curse. In 75AD, the Roman scholar Pliny compared opals to an artist’s paint palette and marvelled at their kaleidoscopic colour-play including red, green, yellow, blue and purple tones.

The Ancient Greeks and Romans believed opal gemstones and opal gemstone jewellery were talismans of fortune-telling, imbued with the power to bring health and hopefulness to their wearer. By the 18th century, opals had developed a strange reputation for bad luck and misfortune. Opals swiftly fell out of favour among 18th and 19th century aesthetes. Take, for example, Queen Victoria’s granddaughter, Queen Alexandra, who removed 11 sensational opals from a tiara she inherited and replaced them for rubies. It is said she wholeheartedly believed that the October birthstone was an unpleasant omen and refused to wear them.

Today, the fortunes of opal have changed, and opal gemstone jewellery is hugely coveted and admired. There are two main types of opal: precious and common. Only the former is used in fine jewellery designs because of its mesmerising rainbow flashes, referred to as ‘play-of-colour’. The world of opals is vast and complex, with the likes of white opal, black opal, fire opal, boulder opal and crystal or water opal playing a role in exceptional fine jewellery pieces. Similarly, describing what makes the ‘perfect’ opal gemstone is difficult and somewhat subjective. It depends on many factors, such as body colour, the rainbow flashes of colour, the patterns these colours make, as well as the brilliance and opacity of the stone itself.

When choosing an opal ring or a pair of opal earrings, it is important to consider the brightness and brilliance of the stone, as well as the flashes of colour and how they are arranged. The most prevalent rainbow colour, sometimes called the ‘dominant’ colour, can influence an opal’s value. Flashes of ruby red command the highest prices, followed by orange, yellow, green, blue, indigo and violet.

These shimmering opal colours are the direct result of its structure. Every opal is made up of microscopic spheres of silica arranged in a grid-like pattern. As light passes through these spheres and the spaces between them it is diffracted, resulting in a fabulous play-of-colour. The order and size of these spheres changes what colours your eyes can see. In some very unusual cases, the way light diffracts can result in exceptional colour patterns that enhance an opal’s value. Some of the most striking are bold stripes of colour, feather shapes and artistic brushstroke-like flashes.

Opal is a soft gemstone that needs to be looked after with tender loving care. Hard knocks can chip this precious gem, so choose a soft cushioned area of your jewellery box and store away from tougher gemstones like sapphire and diamond. Opals can also react badly to high temperatures, perfumes and jewellery cleaners, so take care to avoid these. When choosing opal gemstone jewellery, start with opal earrings and pendants, as these are less likely to be damaged when worn. If you would like a fiery opal dress ring or opal cocktail ring, choose one with a cleverly crafted setting, such as a bezel setting, or surrounded by a protective diamond halo. These methods have long been utilised by expert goldsmiths to protect opals and their rainbow colours.

Opal jewellery is so special because of its incredible uniqueness. No two opal gemstones will ever have the exact same flashes of rainbow colours, which makes an opal necklace or opal ring individual to you. Today, the October birthstone is a confident choice for those whose love of gemstones explores beyond the boundaries of sapphires, emeralds and rubies.