Opal: The October Birthstone
- Thomas Glover
- Oct 8
- 4 min read
Updated: Oct 9
Opal is the enchanting and iridescent gemstone celebrated as the birthstone for October. At Thomas Glover, we are delighted to present a curated selection of antique opal jewellery, each piece capturing the mesmerising play of colour that defines this gem.
Opal is a hydrated form of silica with a non-crystalline structure. What distinguishes it from all other gemstones is play-of-colour: the internal diffraction of light through microscopic silica spheres creates shifting flashes of reds, greens, blues, violets, and gold tones. Because of this, no two opals are alike and each has its own shifting personality. With a hardness of around 5.5–6.5 on the Mohs scale, opals are more delicate than sapphires or diamonds and require gentler wear.
Opals have fascinated humankind since antiquity, admired for their unique ability to capture every colour of the spectrum within a single stone. Pliny the Elder described opal as a gemstone that combined 'the fire of the carbuncle, the brilliant purple of amethyst, and the sea-green of emerald, all shining together in incredible union.' Roman senators and nobles wore opal rings as emblems of power and protection, and the Emperor Constantine is said to have valued them as highly as diamonds or emeralds.
Myths associated with opal were widespread across ancient cultures. In Arabic and Greek traditions, opals were said to fall from the heavens in flashes of lightning, capturing their kaleidoscopic light within. The Greeks were enchanted by this celestial origin and believed opals bestowed foresight and prophecy as gifts from the gods. During the Middle Ages, opals were thought to hold the powers of all gemstones in one, and folklore suggested that blonde women who wore opals would preserve their hair colour. Others even believed the stone could make its wearer invisible.
By the 19th century, the stone’s reputation shifted and opal became known for being supposedly cursed. The superstition is often traced to Sir Walter Scott’s 1829 novel 'Anne of Geierstein', in which an opal amulet loses its colour and brings misfortune upon its owner. In reality, this changeability is simply part of opal’s natural sensitivity to heat and moisture, and not a mark of ill omen but a reflection of its organic delicacy. However, the discovery of vast deposits in Australia during the 1880s transformed the gemstone’s availability and reignited its popularity in jewellery.
The Victorians were interested in the symbolic meaning of gemstones and jewellery, and opal’s shifting rainbow hues made it a perfect medium for emotional expression. In the mid to late 19th century, opals were celebrated as tokens of love and imagination, their ever-changing colours believed to reflect the unpredictable nature of the heart and the mysteries of the natural world. As science and art intertwined, jewellery became a canvas for expressing curiosity about both human emotion and the cosmos itself.
This fascination is embodied in the Victorian Opal and Diamond Comet Brooch, which reflects the era’s preoccupation with astronomy and the celestial. Comets, stars, and crescent moon motifs frequently appeared in late Victorian jewels, inspired as much by new astronomical discoveries as by poetic and romantic symbolism, and in this piece, the opal’s luminous play of colour evokes the fiery tail of a comet streaking across a night sky.
The Edwardian period ushered in a new aesthetic of light and delicate designs. Advances in metalwork allowed jewellers to work in platinum, crafting airy, lace-like settings. In this context, opals' subtle flashes of colour suited the era’s graceful femininity perfectly. The Edwardian Opal and Diamond Drop Earrings embody this delicacy. Their softly articulated drops, framed by delicate diamonds, would have shimmered gently with every turn of the head. These were jewels made to move, catching and releasing light in time with the rhythm of a dance.
Equally elegant, the Edwardian Black Opal and Diamond Ring (c. 1920) shows how jewellers of the period began to experiment with contrast. The inky depth of the black opal’s body tone intensified the brilliance of its blues and greens, while the surrounding diamonds made it a sophisticated choice for the modern Edwardian woman. This period also overlapped with the Art Nouveau movement, whose leading designers embraced opal for its fluidity and ethereal beauty. Its organic shimmer suited their sinuous, nature-inspired designs of whiplash curves and foliate motifs.
By the 1920s, jewellery design had undergone a dramatic transformation. The fluid curves of the Edwardian and Art Nouveau periods gave way to the geometry of Art Deco. In this new aesthetic, opal’s soft iridescence provided a captivating counterbalance to the bold, architectural lines of the era, echoing its fascination with light and motion. For a subtler expression of Deco style, the Art Deco Opal and Pearl Chain (c. 1920) reveals how designers also embraced opal’s decorative versatility.
Opal: What to Look For & How to Care for It
Choosing wisely:
Play-of-colour: Seek bright, varied flashes across the surface.
Body-tone: Black opals (dark backing) intensify colours; white and crystal opals offer airier palettes.
Clarity & condition: Avoid large cracks or fissures. In vintage pieces, check for signs of crazing (fine surface cracks).
Settings: Especially for rings or brooches, prefer bezel or partial bezel settings that protect edges from impact.
Caring for opal jewellery:
Avoid sudden heat or cold, which may stress the stone.
Clean gently with mild soap, lukewarm water, and a soft cloth (no ultrasonic cleaners).
Store separately from other gemstones to avoid scratching.
Few gemstones have inspired as much fascination as opal. Through every era of design, from the sensibility of the Victorians to the delicacy of Edwardian jewellers, opal has remained a symbol of love and imagination. Distinctive, expressive, and endlessly changeable, every opal is unique and tells a different story. At Thomas Glover, we continue to celebrate this remarkable gemstone through our carefully curated selection of antique and vintage opal jewellery.
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