Is it bad luck to wear opal?

That superstition comes from a nineteenth-century novel, not from any tradition of gemology. It did, however, depress opal prices for decades.

Brief contact with water is fine for solid natural opal, but soaking, heat and rapid drying are risky, and doublets and triplets can separate.

Is opal suitable for an engagement ring?

Only with realistic expectations. It will pick up scratches and needs a protective setting and gentle handling.

Gemstones & cuts

Living with opal

Water, silica and the play of color that defined Art Nouveau.

Written by our in-house jewelry team · Updated August 1, 2026 · 5 min read

Art Nouveau enamel pendant with plant motifs beside a mid-century gold brooch on olive velvet — Living with opal

In short

Opal is hydrated silica containing several percent water, 5.5 to 6.5 on the Mohs scale. Its play-of-color comes from light diffracting through microscopic silica spheres. It is soft, sensitive to heat and dryness, and it can craze permanently, so it belongs in pendants and earrings more comfortably than in daily-wear rings.

Nothing else looks like opal, which is exactly why Art Nouveau jewelers reached for it. It behaves like a small piece of weather.

It is also the stone customers ask about most nervously, and reasonably so, because it needs different handling from everything else in the box.

Shop the pieces: Opal, curated and available now.

The stone in brief

Hydrated silica that diffracts light, softer than almost anything else you will set in gold, and worth the care it asks for.

Species and group: Hydrated amorphous silica. Mohs hardness: 5.5 to 6.5. Typical colors: White, grey, black and crystal body colors with flashes of every spectral color.

Contains water, typically around 3 to 10 percent by weight
Play-of-color is diffraction, not fluorescence or coating
Black opal has a dark body tone, which makes the color flash appear brighter
Doublets and triplets, where thin opal is backed or capped, are common and must be identified

Treatments, doublets and assembled stones

With opal the important distinction is not treated versus untreated but solid versus assembled, because a doublet and a solid stone of the same face-up appearance are priced worlds apart.

Our gemologist examines every stone before a piece is listed, and the description states what is known and what cannot be determined without a laboratory report.

Smoke and sugar treatments to darken body tone in some material
Impregnation with oil, wax or resin
Doublets and triplets: assembled stones rather than treatments, and priced very differently
Synthetic and imitation opal exists and shows a regular columnar or lizard-skin pattern under magnification

“An opal is not a stone you buy from a photograph. It has to move in front of you.”
Our estate jewelry team

Checking an opal in the setting

Almost everything you need to know about an opal is visible from the side and from a tilt, which is lucky, because most antique opals are set closed-back.

Look at the stone from the side: a straight joining line means a doublet or triplet
Natural play-of-color moves and changes as you tilt the stone, rather than staying fixed
Very regular, repeating color patches suggest a synthetic
Fine surface crazing looks like a dried riverbed and cannot be polished out

Loose antique cut garnet, emerald, sapphire and diamond stones on a paper parcel — Gemstones & cuts — from the pieces and workshop notes behind this guide.

Opal and Art Nouveau

Opal is the signature stone of Art Nouveau, set with plique-a-jour enamel and gold in pendants and brooches, and it stayed popular in Edwardian and Arts and Crafts jewelry.

Because opal is soft, antique opals often show fine scratches and worn edges. We report crazing honestly and we photograph the stone under macro from more than one angle before listing.

Frequently asked questions

Is it bad luck to wear opal?: That superstition comes from a nineteenth-century novel, not from any tradition of gemology. It did, however, depress opal prices for decades.
Can opal get wet?: Brief contact with water is fine for solid natural opal, but soaking, heat and rapid drying are risky, and doublets and triplets can separate.
Is opal suitable for an engagement ring?: Only with realistic expectations. It will pick up scratches and needs a protective setting and gentle handling.

Written by our estate jewelry team and reviewed by our in-house gemologist. We have been buying and selling European antique jewelry since 1973.

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