If you were born in October, you have the most individual birthstone on the calendar. Opal refuses to settle on a single colour: tilt it and it flashes blue, green, pink and orange at once, and no two stones are alike. It is the only birthstone where the piece you buy is genuinely one of a kind.

October also has a second stone, tourmaline, and the two could hardly be more different to live with. That difference matters more than the usual gemstone trivia, because it decides what you can sensibly wear. This guide covers how to wear each, how to style opal with gold, what to check before buying, and how to look after it. For every month and stone, see our birthstones by month chart.

Three ways to wear an October birthstone

As a piece in its own right. An opal pendant is the classic, and the safest way to wear a soft stone. Because opal contains every colour at once it never clashes with what you already own, and it changes as you move, which is part of the pleasure of it. On a fine gold chain, one opal is enough.

Set small into something personalised. A small opal set into an engraved tag, beside an initial, or hung as a charm from a bracelet. This is our favourite way with October, partly because it is beautiful and partly because a smaller stone in a protective setting is far more practical for a stone this soft. It is also the natural way to mark more than one person, a stone each for your children along a single bar.

Layered, or in a ring if you choose tourmaline. An opal pendant layered against plain gold chains looks wonderful. But if what you actually want is a ring you never take off, choose tourmaline instead. It is significantly harder, and October is generous enough to give you the option.

Styling opal with your everyday gold

Opal is the great chameleon of birthstones. Because its play of colour contains a little of everything, it is almost impossible to clash with, which makes it far easier to wear than people expect from such a distinctive stone.

Yellow gold warms an opal and brings out its orange and pink flashes, giving a softer, more vintage feel. White gold does the opposite, cooling the setting so the blues and greens come forward and the whole thing reads crisper and more modern. Rose gold is the romantic choice, and particularly lovely with the pinker opals.

A practical tip worth more than any styling rule: look at the stone in daylight and in lamplight before deciding on the metal, because an opal's dominant colour can shift noticeably between the two.

Solid opal, doublets and triplets

This is the single most useful thing to know before buying opal jewellery, and it is rarely explained. A solid opal is exactly that: one piece of opal, all the way through. A doublet is a thin slice of opal glued to a dark backing to make the colour pop. A triplet adds a clear cap on top as well.

Doublets and triplets look striking and cost far less, but they are composite stones: water can eventually get between the layers, and they cannot be treated like a solid stone. Neither is dishonest, and both have their place, but the price difference is enormous and the two should never be confused. Always ask which you are buying.

The types of opal, and where they come from

Opal's flashes of colour, known as play of colour, are caused by microscopic spheres of silica inside the stone bending light like a prism. The body colour underneath is what separates the types. White opal has a pale background and a softer, milkier look. Black opal has a dark body that makes the colours leap out, and is the most prized and most expensive. Fire opal is a warm orange to red, often transparent, and may show little play of colour at all. Boulder opal keeps some of its host ironstone attached.

Australia has produced the great majority of the world's fine opal for over a century, with black opal coming principally from Lightning Ridge in New South Wales. Fire opal is largely Mexican, and Ethiopia has become a significant source in recent decades.

The colours of tourmaline

Tourmaline's range is unmatched. It occurs in more colours than any other gemstone, which means an October birthstone can be very nearly any shade you like. Raspberry pink tourmaline, sometimes called rubellite, and cool forest green tourmaline are the most familiar. Then there is watermelon tourmaline, pink at the centre and green at the rim within a single crystal, usually cut in slices so both colours show.

Rarest and most coveted is Paraiba, a neon blue-green found originally in Brazil and coloured by traces of copper. It is among the most valuable coloured stones in the world, and unmistakable once you have seen one.

Is opal really unlucky?

No, and the superstition is surprisingly recent. For most of history opal was considered one of the luckiest stones there was, a symbol of hope and creativity, thought to hold the virtues of every other gem because it contained every colour. Its bad reputation is usually traced to a single Victorian novel, Sir Walter Scott's Anne of Geierstein of 1829, in which an opal loses its colour and its owner dies. The story caught the public imagination and, so the tale goes, opal sales fell for years afterwards. It is fiction. If October is your month, opal is simply your stone.

Caring for opal

Opal contains water, which is why it needs slightly different care from other stones. Keep it away from prolonged heat and very dry air, both of which can dry it out, and away from perfume, hairspray and household chemicals. Never put it in an ultrasonic cleaner. Clean it with a soft, damp cloth and nothing more. Put it on last and take it off first, and store it away from harder stones that could scratch it. Treated kindly, an opal keeps its fire indefinitely.

October birthstone questions

What is the October birthstone?

October has two birthstones: opal, famous for its shifting play of colour, and tourmaline, which occurs in more colours than any other gem. Opal is the traditional choice; tourmaline is the harder-wearing alternative.

How do you wear an October birthstone?

Opal is best worn as a pendant or earrings, ideally in a bezel setting that protects the edges of the stone. It also works beautifully set small into something personalised, beside an initial or on an engraved tag. If you want a ring for everyday wear, choose tourmaline instead, as it is considerably harder.

What colour is opal?

Opal shows a shifting play of every spectral colour, blue, green, pink and orange, over a body that may be white, black or fiery orange. Because the colour moves as the stone moves, no two opals are alike.

Is opal unlucky?

No. For most of history opal was considered lucky, a symbol of hope and creativity. The superstition dates only to a Victorian novel, Sir Walter Scott's Anne of Geierstein (1829), and has no basis at all.

What is the difference between solid opal, a doublet and a triplet?

A solid opal is one piece of opal throughout. A doublet is a thin slice of opal glued to a dark backing to intensify the colour, and a triplet adds a clear protective cap on top. Doublets and triplets cost far less but are composite stones and cannot be cared for in the same way, so always ask which you are buying.

Is opal good for everyday jewellery?

Opal is soft, at 5.5 to 6.5, and holds water, so it is best worn as a necklace, pendant or earrings rather than a ring, set in a protective bezel and kept away from heat and chemicals. For an everyday ring, tourmaline is the tougher October choice.