2027 Forecast

October · Iridescent and multicoloured

October birthstone: Opal

The October birthstones are Opal and Tourmaline — the month carries 2 official modern stones, which is why sources disagree about it. The traditional list keeps only Opal; Tourmaline was added later.

1912 jewelers’ list
Opal or tourmaline · Kansas City
Older lists
Beryl · 8 of 8 Kunz’s tally of 8 old lists
October births
8.53% #4 of 12 months, US 2000–2014

Kunz 1913; US births 2000–2014.

The months either side, and the same month in flowers: September birthstone, November birthstone and October birth flower.

All twelve months, modern and traditional lists in one table: birthstones by month.

October Birthstones: Opal and Tourmaline
Modern birthstone Opal, Tourmaline
Traditional birthstone Opal
Color Iridescent and multicoloured
Birth flower Marigold and Cosmos
Zodiac signs Libra, Scorpio
Hardness (Mohs) 5.5–6.5

Opal acquired a reputation for bad luck after Walter Scott's 1829 novel Anne of Geierstein, in which an opal loses its fire and its owner dies. Sales in Europe reportedly halved. The superstition has no earlier source.

October stones in detail

Opal

Composition Hydrated silica (SiO₂·nH₂O) — 3 to 21 percent water by weight
Hardness · Crystal system 5.5–6.5 · Amorphous
Mined in Australia, Ethiopia, Mexico, Brazil

The play of color comes from stacked silica spheres diffracting light — the same physics as a butterfly wing, not pigment.

Traditionally linked to imagination, emotional range and creative flow.

Care. Damp cloth only. Never ultrasonic, never steam, never leave it in a hot car — opal holds up to 21 percent water and crazes if it dries out.

Spotting a fake. Doublets and triplets — a thin opal slice glued to a dark backing — are common and much cheaper. Look at the stone edge-on: a doublet shows a flat glue line.

Tourmaline

Composition Complex boron silicate with variable aluminum, iron, magnesium, lithium
Hardness · Crystal system 7–7.5 · Trigonal
Mined in Brazil, Nigeria, Mozambique, Afghanistan, USA (Maine)

Tourmaline develops an electric charge when heated or squeezed. Watermelon tourmaline grows pink at the core and green at the rim.

Traditionally associated with protection and grounding, especially the black variety.

Care. Warm soapy water. Avoid ultrasonic if the stone has inclusions, which many do.

Spotting a fake. Genuine tourmaline is pyroelectric — warm it and it attracts dust and small paper fragments. Glass does nothing.

The story of the October stones

Opal was treasured in Rome: Pliny described it as holding the fire of the carbuncle, the purple of amethyst and the sea-green of emerald in one stone. Most of the world's precious opal has come from Australia since the finds of the late nineteenth century, and in 1993 it was named the national gemstone. Tourmaline — from the Sinhalese turmali, a name for mixed colored gems — was added to October in the twentieth century, with pink as the usual choice.

Choosing an October stone

Opal comes in several kinds: white opal is the most common, black opal from Lightning Ridge in Australia is the most valuable, and boulder opal keeps a layer of its host rock. Ethiopian opal is bright and affordable but can absorb water and briefly lose its color play. Tourmaline is the tougher October option and comes in almost every color; the neon-blue Paraíba variety outprices most sapphires.

Primary source

October in George Kunz’s Curious Lore of Precious Stones (1913)

The verse for October
“October’s child is born for woe, And life’s vicissitudes must know; But lay a beryl on her breast, And Hope will lull those woes to rest.”
Kunz on the 1912 list
“For October neither the tourmaline nor the opal is as appropriate as the beryl, while for June we should prefer the asteria to the moonstone as a substitute for the pearl.”
George Frederick Kunz, The Curious Lore of Precious Stones (Philadelphia and London: J. B. Lippincott, 1913), chapter IX, “Birth-Stones” — read the original text. Kunz’s traditional stone for October is beryl, and the jewelers’ list adopted in Kansas City in 1912 gives opal (alternative: tourmaline). In his tally of eight older lists, October went to beryl in 8 of them, aquamarine in 5, opal in 1 — some lists give a month two stones. Which lists Kunz compared, and where the verses come from →

October birth flowers

Marigold

Traditionally signifies warmth and fierce affection.

Cosmos

Traditionally signifies order and tranquillity.

More on October birth flowers →

If you go by zodiac sign instead

October spans two signs — Libra and Scorpio — and the zodiac stone list does not match the monthly one. Which applies to you depends on the day, not just the month.

Libra stones · Scorpio stones

Questions about the October birthstone

What is the birthstone for October?

The modern October birthstones are Opal and Tourmaline.

What color is the October birthstone?

Iridescent and multicoloured.

What is the October birth flower?

Marigold and Cosmos; the marigold traditionally signifies warmth and fierce affection.

Is Opal hard enough to wear every day?

Opal rates 5.5–6.5 on the Mohs scale. It can be worn often, with care around heat and dry air, which make it craze.

What zodiac signs fall in October?

Libra and Scorpio.

Other months

January February March April May June July August September November December

Measured against our reference of 43 stones

The October stones, by hardness

Opal · modern and traditional Mohs 5.5–6.5 · -0.35 vs average · wear with care
Tourmaline · modern and alternative Mohs 7–7.5 · +0.9 vs average · everyday ring
Average across all 43 stones Mohs 6.35
Modern and traditional Opal in both
October birthstones on the Mohs hardness scale
October birthstones on the Mohs hardness scaleMohs scale from talc (1) to diamond (10) with the October birthstones marked: Opal 5.5–6.5, Tourmaline 7–7.5.Opal: Mohs 5.5–6.5Opal 5.5–6.5Tourmaline: Mohs 7–7.5Tourmaline 7–7.5Garnet: Mohs 6.5–7.5Amethyst: Mohs 7Citrine: Mohs 7Rose Quartz: Mohs 7Clear Quartz: Mohs 7Smoky Quartz: Mohs 7Aquamarine: Mohs 7.5–8Emerald: Mohs 7.5–8Bloodstone: Mohs 6.5–7Peridot: Mohs 6.5–7Sardonyx: Mohs 6.5–7Zircon: Mohs 6–7.5Carnelian: Mohs 6.5–7Onyx: Mohs 6.5–7Agate: Mohs 6.5–7Tiger's Eye: Mohs 6.5–7Aventurine: Mohs 6.5–7Diamond: Mohs 10Pearl: Mohs 2.5–4.5Alexandrite: Mohs 8.5Moonstone: Mohs 6–6.5Labradorite: Mohs 6–6.5Pyrite: Mohs 6–6.5Ruby: Mohs 9Sapphire: Mohs 9Spinel: Mohs 8Topaz: Mohs 8Opal: Mohs 5.5–6.5Rhodonite: Mohs 5.5–6.5Tourmaline: Mohs 7–7.5Turquoise: Mohs 5–6Lapis Lazuli: Mohs 5–6Hematite: Mohs 5–6Tanzanite: Mohs 6–7Jade: Mohs 6–7Obsidian: Mohs 5–5.5Malachite: Mohs 3.5–4Amber: Mohs 2–2.5Selenite: Mohs 2Fluorite: Mohs 4Sodalite: Mohs 5.5–6Kyanite: Mohs 4.5–7Lepidolite: Mohs 2.5–31Talc2Gypsum3Calcite4Fluorite5Apatite6Orthoclase7Quartz8Topaz9Corundum10Diamondfingernail 2.5window glass 5.5household dust (quartz) 7Source: Mohs scale minerals · ranges from our 43-stone referenceastrohot.com
October birthstones on the Mohs hardness scaleMohs scale from talc (1) to diamond (10) with the October birthstones marked: Opal 5.5–6.5, Tourmaline 7–7.5.Opal: Mohs 5.5–6.5Opal 5.5–6.5Tourmaline: Mohs 7–7.5Tourmaline 7–7.51Talc2Gypsum3Calcite4Fluorite5Apatite6Orthoclase7Quartz8Topaz9Corundum10Diamondfingernail 2.5glass 5.5dust 7Source: Mohs scale minerals · ranges from our 43-stone referenceastrohot.com

October on the scale: Opal 5.5–6.5, Tourmaline 7–7.5. Of the twelve months’ first-listed modern stones, Opal is the 10th hardest.

Opal: Hydrated silica (SiO₂·nH₂O) — 3 to 21 percent water by weight. Crystal system Amorphous. Below Mohs 7 it is scratched by ordinary airborne dust — quartz sits at 7.

Who this month covers

Days in October 31
Libra · October 1–22 71.5% of October births
Scorpio · October 23–31 28.5% of October births

October is mostly Libra territory: the sign claims 22 of its days, leaving Scorpio the last 9, and in US births for 2000–2014 its share of the month was 71.5%. Exact sign dates →

Sources

  1. George Frederick Kunz, The Curious Lore of Precious Stones (Philadelphia and London: J. B. Lippincott, 1913), chapter IX, “Birth-Stones”

Statements of fact on this page were checked against these sources in October 2026. How we choose and check sources: editorial policy.

Cite this page

AstroHot. “October Birthstones: Opal and Tourmaline.” Accessed October 28, 2026. https://astrohot.com/birthstones/by-month/october/

For Wikipedia {{cite web |title=October Birthstones: Opal and Tourmaline |url=https://astrohot.com/birthstones/by-month/october/ |website=AstroHot |access-date=2026-10-28}}