What Is the October Birthstone? Opal & Tourmaline Explained
The October birthstone is opal — and October is one of only a handful of months with a second, alternative birthstone: tourmaline. Opal is the traditional and far more widely recognised of the two, known for play-of-colour, the shifting flashes of green, blue, pink and orange that move across the stone. It's also Australia's national gemstone, which gives it a particular resonance here.
Opal: October's primary birthstone
Opal has been October's birthstone for well over a century, formalised in the modern birthstone lists jewellers still work from today. What sets it apart from every other birthstone is that no two opals are alike — and, in a sense, no single opal is even quite the same twice, because its colours shift depending on how the light strikes it.
Most gems are prized for consistency: a sapphire's steady blue, a ruby's steady red. Opal is prized for exactly the opposite.
Why opal changes colour
Opal is made of microscopic silica spheres, stacked in a regular grid. Those spheres happen to be close in size to the wavelength of visible light, so when light passes through them it diffracts — splitting into its component colours, the way light splits through a prism. Change the angle, and you change which colours reach your eye. That's play-of-colour, and it's the reason opal looks alive in a way no other gem quite manages.
Tourmaline: October's second birthstone
Modern lists give October a second option. Tourmaline occurs in a wider colour range than almost any other gem — pink, green, blue, and the striking "watermelon" material that shows pink and green within a single crystal. It's tougher than opal too, at 7–7.5 on the Mohs scale.
Irosk doesn't stock tourmaline; our October collection is built entirely around opal. But it's worth knowing the alternative exists.
White opal and black opal
Opal is classified by body tone — the background behind the colour flashes.
White opal has a pale, milky body. The colour play appears soft and diffused, giving a gentle luminosity. It's the more common type and the easier of the two to wear daily.
Black opal has a dark body tone. Because colour reads more strongly against a dark background, the same flashes appear far more vivid and dramatic. It's the more sought-after type, and Lightning Ridge in New South Wales is its most famous source.
We set both in 925 sterling silver — browse our opal jewellery collection to compare them side by side.
Opal, Australia's national gemstone
Opal isn't a borrowed tradition here. It's Australia's national gemstone, and the great fields are Australian: Coober Pedy in South Australia for white and light opal, Lightning Ridge in New South Wales for black opal, and Queensland for boulder opal. If you're buying an October birthstone in Australia, you're buying something with genuine local roots. Read the fuller story in our article on Australia's national gemstone.
October's zodiac signs
October spans two star signs, and neither sits neatly inside the month. Libra runs 23 September to 22 October, so Libras born in September have sapphire and those born in October have opal. Scorpio runs 23 October to 21 November, so Scorpios born in October have opal and those born in November have citrine. Shop Libra jewellery and Scorpio jewellery.
Meaning and symbolism
Opal has long been associated in folklore with hope, creativity and imagination, its shifting colours traditionally read as a symbol of change and possibility. There's also a persistent superstition that opal is unlucky for anyone not born in October — an idea widely traced to a nineteenth-century novel rather than to any older tradition. These associations belong to culture and belief rather than fact, and we offer them in that spirit.
Caring for October's birthstone
Opal needs more care than most gems, and it's worth knowing why before you buy. At 5.5–6.5 on the Mohs scale it's softer than sapphire, ruby or citrine, and it holds water within its structure. Never put opal in an ultrasonic cleaner. Avoid sudden temperature changes, which can cause crazing. Store it away from harder stones. Clean it with a soft, slightly damp cloth. And choose the setting for the wear — opal earrings and opal pendants take far less punishment than rings.
Shopping for October birthstone jewellery
Start with our October birthstone jewellery collection, or browse the full opal jewellery range in 925 sterling silver. Shop by style: rings, earrings, necklaces, bracelets. For the full picture on the stone, read our complete guide to opal, and see what drives opal prices.
Frequently asked questions
What is the birthstone for October?
Opal is October's birthstone. It's known for play-of-colour — the shifting flashes of green, blue, pink and orange that appear as the stone moves. Tourmaline is recognised as a second, alternative October birthstone on modern lists.
Does October have two birthstones?
Yes. October has opal as its primary, traditional birthstone, and tourmaline as a secondary alternative. Opal is by far the more widely recognised, and it's the stone most October birthstone jewellery is set with.
What colour is the October birthstone?
Opal doesn't have a single colour — that's the point of it. Its body tone can be milky white or dark, and against that background it flashes green, blue, pink and orange depending on the angle of the light. Tourmaline, the secondary stone, occurs in pink, green, blue and multi-coloured varieties.
Written by the Irosk team. Irosk is a family-owned Australian jewellery brand based in Brisbane, specialising in 925 sterling silver gemstone jewellery. We've been crafting birthstone pieces since 2021.