October's Birthstone: Opal, the Stone That Changes With the Light
October has two birthstones. Why opal is the older and stranger of the pair, what makes it softer than most gems, and how to wear one every day.
5 min read
Most gemstones have a colour. Opal has a behaviour. Tilt it and flashes of green, blue and pink move across the surface, then disappear, then come back somewhere else. No two stones do it the same way, and the same stone looks different under a kitchen light and a winter window.
That's why it has been October's birthstone for as long as birthstones have been listed by month — and why it's worth understanding before you buy one or give one.
What is October's birthstone?
October has two: opal and tourmaline. Opal is the traditional stone. Tourmaline was added later as a harder, more colourful alternative.
The two could hardly be more different. Tourmaline is transparent and comes in almost every colour. Opal is milky or glassy, and its colour isn't in the stone so much as on it — a shifting play of light across a pale body.
| Opal | Tourmaline | |
|---|---|---|
| Look | Milky or glassy body with flashes of colour that move as it turns | Transparent, one or more solid colours |
| Hardness (Mohs) | 5.5–6.5 | 7–7.5 |
| Best for | Pieces worn with a little care, in protective settings | Everyday rings that take knocks |
| Main source | Australia, which produces roughly 90–95% of the world's precious opal | Brazil, Afghanistan, Nigeria, Madagascar |
Our October Opal Birthstone Ring (£48.75) uses opal, because that's the stone most people mean when they say "October" — specifically a lab-created opal, which is explained below.
Where does opal's colour come from?
From its structure, not from pigment. Opal is made of microscopic spheres of silica packed together with water. Light passing between those spheres splits into its colours, the same way it does through a prism, and which colour you see depends on the angle.
That's also why photographs never quite capture it. A camera freezes one angle; the stone is only doing its job when it moves.
Natural opal also holds water inside it — a few percent in most gem stones, sometimes considerably more. It's the water that makes mined opal behave differently from almost every other gem, and it's the reason for most of the care advice further down.
Is a lab-created opal real opal?
It's opal made rather than mined. The colour comes from the same principle — light split by a regular structure of tiny spheres — but the structure is grown under controlled conditions instead of forming in the ground over millions of years.
The practical differences are easy to state. A lab-created opal shows a steadier, more even flash than most mined stones, which vary wildly from one to the next. It's also far more affordable: a natural opal with this much colour would cost many times the price of the ring.
We say which it is because it matters. The stone in the October ring is lab-created, and so is the price.
Is opal too soft to wear every day?
Opal, natural or lab-created, is softer than most gems — natural opal sits at 5.5 to 6.5 on the Mohs scale, where sapphire sits at 9 — so it will pick up scratches from harder stones and can crack if it's knocked hard or dries out quickly. But softer isn't the same as fragile, and the setting makes most of the difference.
An exposed opal on raised prongs takes every knock directly. An opal sitting inside a full metal rim is protected on all sides; the metal meets the door frame before the stone does.
That's the reason the October ring is made the way it is. The opal sits in a raised gold-plated bezel that wraps its whole edge, on a sterling silver band that tapers down to a slim shank at the back. It's designed to be worn, not kept in a box.
What does opal mean?
For most of its history, opal was a lucky stone. Roman writers prized it because it seemed to hold the colours of every other gem at once — the red of one, the green of another, the violet of a third, all in a single stone.
Its bad reputation is surprisingly recent, and it comes from fiction. In 1829 Walter Scott published Anne of Geierstein, a novel in which an opal belonging to one of the characters loses its colour when touched by holy water, and its owner dies soon after. Readers took it to heart, and opal's reputation in Europe suffered for much of the century that followed.
Today opal is usually associated with creativity and imagination — which suits a stone that never looks the same way twice.
Who is an opal ring for?
Anyone born in October, obviously. But it's also one of the most wearable birthstones for people who don't usually wear stones at all.
The pale body reads almost like polished metal from a distance, so an opal ring sits comfortably next to plain silver. It works on a man's hand as easily as a woman's — the flash of colour only shows up close, which makes it quieter than a saturated ruby or sapphire.
Sizes are listed in US measurements. The Ring Size Guide converts from UK letters, and it's worth checking before ordering: this is a small-batch ring, and not every size is still available.
How do you look after an opal?
Gently, and mostly by avoiding a few specific things. Much of the usual advice comes from natural opal's water content, which a lab-created stone doesn't share to the same degree — but the same gentle care is sensible either way.
Do: clean it with lukewarm water, a drop of mild soap and a soft cloth, then dry it. Store it on its own in a pouch rather than loose in a box with other jewellery. Take it off for the gym, gardening and anything involving cleaning products.
Don't: use ultrasonic or steam cleaners, which can crack it. Leave it on a radiator, a sunny windowsill or a hot car dashboard — prolonged dry heat pulls water out of the stone and can cause fine surface cracks. Plunge it from cold into hot water.
The silver band needs its own care, which is different from the stone's. How to Clean Sterling Silver Jewellery at Home covers the silver; just keep any polishing cloth or cleaner away from the opal itself.
The October ring is one of twelve in our Birthstone Rings series, all made in the same shape and all £48.75, so they stack cleanly on one finger. The pale opal is the easiest of the twelve to pair: next to the deep blue of the September Sapphire, the golden November Topaz or the December Turquoise, it reads as the quiet one. Two months on one hand — yours and someone else's — is a better gift than either ring on its own. Every piece is handmade in our Istanbul workshop and shipped from London, and the whole collection is currently part of the Archive Sale.
For the other eleven months, Birthstone Guide: Find Your Gemstone by Month goes through them one by one.