October · Iridescent and multicoloured

October birthstone: Opal

October carries 2 official stones — Opal, Tourmaline.

Modern birthstone Opal, Tourmaline
Traditional birthstone Opal
Colour 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 colour 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 aluminium, 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.

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?

Opal, Tourmaline in the modern list.

What colour is the October birthstone?

Iridescent and multicoloured.

What is the October birth flower?

Marigold and Cosmos — signifying warmth and fierce affection.

Is it hard enough to wear every day?

Opal sits at 5.5–6.5 on the Mohs scale. Too soft for a ring worn daily — better in a pendant or earrings.

Other months

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