Opal Gemstones

What makes an opal gemstone different from other stones?

Opal is the only gemstone that displays play-of-colour — an internal diffraction of light caused by microscopic silica spheres arranged in a regular lattice. Unlike faceted stones that rely on cut geometry for brilliance, opal produces shifting spectral flashes entirely from within its structure. This optical phenomenon, known as adularescence in related stones but termed play-of-colour specifically in opal, means no two opals are alike. The pattern, intensity, and colour range of that internal display are the primary quality indicators, alongside body tone — the background colour that ranges from white through mid-grey to black. Black opals, predominantly sourced from Lightning Ridge in New South Wales, Australia, are considered the rarest, as the dark body tone deepens the contrast of the colour flashes. Ethiopian Welo opals offer a more transparent, crystal-like body tone and are increasingly sought after. Each opal in our inventory is assessed individually, and a certificate of authenticity is provided with every stone.

How to choose a quality opal — what to look for

When selecting an opal, four characteristics guide the assessment: play-of-colour intensity, pattern, body tone, and clarity. An opal displaying red within its play-of-colour palette is generally more desirable than one showing only blue or green, as red is the rarest spectral flash. Pattern names such as harlequin, pinfire, and rolling flash describe the arrangement and movement of colour across the stone — harlequin being among the most prized for its mosaic-like regularity. Body tone runs on a scale from N1 (black) to N9 (white or crystal), with darker tones (N1–N4) commanding higher prices per carat. Clarity matters too: natural crazing, fine internal fractures that can appear over time, is worth checking before purchase. All opals in our range are individually described so that the characteristics above are transparent before any decision is made. Loose opals are available for 30 days with no questions asked and no exclusions.

What does a loose opal gemstone cost in the UK?

Opal pricing varies more dramatically than almost any other gemstone because value is so dependent on the individual stone's play-of-colour. A fine black opal with vivid, broad-pattern colour display can reach thousands of pounds per carat, while a white or crystal opal with moderate colour may be significantly more accessible. Body tone, colour range, and pattern all affect price-per-carat considerably. When setting a budget, it is worth deciding which characteristic matters most — intensity, rarity of body tone, or carat size — and balancing accordingly. For context, Bridebook's 2026 UK average engagement ring spend of £2,247 provides one benchmark, though opals are also set into dress rings, pendants, and gift pieces where different budgets apply. Our range spans multiple price points so that the opal's visual character, rather than a single metric, drives the selection.

Is an opal durable enough for daily wear?

Opal rates 5.5–6.5 on the Mohs hardness scale, which places it below sapphire, ruby, and diamond. It also has a relatively low specific gravity and contains water within its silica structure — typically 3–21% by weight — which means it can be sensitive to sudden temperature changes, low humidity, and ultrasonic cleaning. For a ring worn daily, a bezel or protective rub-over setting is advisable rather than a claw setting that leaves the opal's edge exposed. Opal is very well suited to pendants, earrings, and dress rings worn occasionally. When an opal from our range is set into one of our rings at the Hatton Garden workshop, the setting style can be discussed during the consultation to ensure the stone is properly protected. The finished ring is then hallmarked at the London Assay Office before insured UK delivery.

Natural versus lab-created opal — what is the difference?

Natural opals form over millions of years as silica-rich water percolates through rock and slowly deposits microscopic spheres in cavities. Lab-created opals replicate this silica-sphere structure in a controlled environment, producing consistent play-of-colour at a lower price point. The optical phenomenon is the same, but natural opals retain the individuality that comes from geological formation — no two stones share an identical pattern. Lab-created opals tend to have a more uniform, sometimes almost synthetic-looking pattern on close inspection. Both are available within our opal range. Natural opals carry certificates of authenticity confirming their origin and characteristics. The choice comes down to preference for provenance and uniqueness versus budget-conscious consistency of colour display.