Opal is the traditional October birthstone, sharing the month with tourmaline in modern lists maintained by the American Gem Trade Association (AGTA), the Jewelers of America (JA), and the National Association of Goldsmiths in the United Kingdom. Both stones appear in GIA's birthstone reference, and most retailers offer customers either or both as October options. Opal is the older designation, present in lists going back to the medieval Christian tradition that derived monthly stones from the breastplate of the Hebrew high priest as described in the Book of Exodus. Tourmaline was added to the modern list in the twentieth century to provide an alternative for buyers who prefer a transparent faceted stone or who are concerned about opal's relative softness.

Opal in the October position

Among the precious-opal varieties suitable for October birthstone jewellery, three categories cover the bulk of the trade. Australian black opal — particularly fine Lightning Ridge material — provides the most intense play of colour and the strongest dark-body contrast, and is the premium choice for buyers willing to pay for top-quality stones. White opal from Coober Pedy and other Australian fields, with a lighter body and characteristic pastel play of colour, is the most accessible Australian option and accounts for the bulk of mainstream October birthstone retail. Ethiopian Welo opal, available in white, honey, brown, chocolate, and treated black body colours, has expanded the choice substantially since 2008 and offers exceptional brightness at competitive price points.

Fire opal — most often Mexican in origin — is also recognised under the October designation, and provides a transparent orange or red alternative for buyers who prefer the look of a faceted gemstone over the cabochon presentation typical of precious play-of-colour opal. Crystal opal, with its transparent body and play of colour visible through the stone, occupies a middle position and has its own collector following.

Care implications for everyday wear

Opal's relatively low hardness (5.5 to 6.5 on the Mohs scale) and its water-content sensitivity mean that October birthstone jewellery should be selected and worn with these material properties in mind. Pendants, earrings, and brooches present opal in protected settings where impact and abrasion are unlikely. Rings expose the stone to the kind of incidental impact that can chip or crack opal, and bezel rather than prong settings are strongly preferred for ring use. Buyers who want everyday-wear durability with an October association may find tourmaline a more practical choice for a solitaire ring, while reserving opal for occasional-wear pieces.

Hydrophane Ethiopian opal warrants particular caution: the material absorbs water and can change appearance significantly when wet. Steam and ultrasonic cleaning are absolutely contraindicated, and even the splash exposure of regular hand-washing requires the stone to be removed in advance. For solid Australian opal the care protocol is less restrictive but still requires avoidance of thermal shock, harsh chemicals, and prolonged immersion.

Tourmaline as the alternative

Tourmaline was added to the October birthstone list in the twentieth century, partly to address the durability concern with opal and partly to take advantage of tourmaline's extraordinary range of colour. The same species, in chemical terms, can produce pinks, greens, blues, the cuprian Paraíba blue-greens, the chrome greens of East Africa, and a long list of other hues. For buyers who want a transparent faceted October stone, tourmaline is the natural choice, and it covers a price range from very affordable to high-investment Paraíba material. See the separate entries on tourmaline and the various variety-specific tourmaline articles for material reference.

In the trade

October birthstone retail is steady year-round but typically peaks around the autumn gift season and around October itself. For working jewellers, stocking a selection across both opal and tourmaline provides the most flexibility, with at least one piece in fine Australian black opal, accessible white opal, Ethiopian Welo, and a representative range of tourmaline colours. The October association is one of the strongest birthstone-driven retail categories, partly because both stones are visually striking and partly because the choice between two distinct materials gives the conversation between jeweller and customer more substance than a single-stone month.

For octave-significant gift occasions — important birthdays, anniversaries with October birth dates — fine Lightning Ridge black opal or top-grade Welo material remains the premium recommendation, with care guidance appropriate to the wearer's lifestyle. See also the opal overview for material reference and the separate tourmaline entries for the alternative.

Further reading

• GIA — October birthstone reference
• GIA — opal reference
• International Gem Society — opal and tourmaline reference