About this stone
Color
WhiteBlueGreenPinkMulti-color Play
Origin
Australia (Coober Pedy, Lightning Ridge, Andamooka)
Mohs hardness
5.5–6.5
Treatment categories
Natural
Industry-standard treatment
Natural — Australian opal is universally untreated; smoke-treated welo material is Ethiopian origin and disclosed separately
Mineral chemistry
Hydrated amorphous silica (SiO2·nH2O), water content 3–10%
Crystal system
Amorphous
Stone family
Opal
Birthstone
October
Common cuts
Faceted RoundRound
Common sizes
3mm4mm6mm
Care notes
Moderate hardness (Mohs 5.5–6.5) with water content. Avoid ultrasonic, steam, dry/hot environments, and harsh chemicals; mild soap and soft cloth.
Related stones
Opal, Welo Opal, Boulder Opal, Pink Opal
Frequently asked questions
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Where does Australian opal come from?
Australia is the world's primary source of precious opal. The major deposits are Lightning Ridge in New South Wales (black opal — dark body tone with play-of-color), the Queensland boulder fields including Winton and Quilpie (boulder opal — opal forming within ironstone matrix), Coober Pedy and Mintabie in South Australia (white and light opal), and Andamooka (matrix opal). Australian deposits formed over the past 30 million years as silica-rich groundwater deposited in sedimentary basins. Where the specific deposit is known for a Dakota strand, it should appear in the listing specifications table. -
What's the difference between Australian opal and Ethiopian opal?
Both are real opal — hydrated amorphous silica — but they come from different geological settings and behave differently. Australian opal is "sedimentary" opal that formed slowly in stable conditions; it's generally stable and doesn't significantly absorb water from the environment. Ethiopian opal (particularly Welo opal) is "hydrophane" — it can absorb water from the environment and temporarily change appearance, sometimes losing play-of-color until it dries. Designers buying Australian specifically often want the stability profile. The two types should not be substituted for each other; the origin should be disclosed. -
Will my opal beads crack or craze?
Most stable Australian opal stays stable in ordinary wear. Crazing — the development of fine surface cracks — happens when opal loses too much of its internal water content too quickly, usually from prolonged dry heat, very low humidity, or rapid temperature changes. Most opal that's going to craze does so within 12–18 months after cutting; stones that have been stable for that long generally remain stable. Reasonable care (avoid ultrasonics, avoid direct heat, avoid arid long-term storage) keeps opal beads sound for decades. -
How durable is Australian opal for daily wear?
Mohs 5.5–6.5, which is softer than most of Dakota's catalog (agate, jasper, quartz varieties run 6.5–7). Opal beads are well-suited for necklaces and earrings; bracelets are workable with reasonable care; rings require more caution because of impact and abrasion exposure. Boulder opal and matrix opal are more impact-resistant than precious black opal because the ironstone or host-rock matrix provides structural support. -
Is Australian opal treated or natural?
Dakota's active Australian opal inventory tags as natural across the strands tagged. Australian opal is generally sold untreated — the natural play-of-color, body tone, and matrix character are intrinsic. Treatments that exist in the broader opal market (smoke treatment, sugar-acid treatment, polymer impregnation) are more common in Ethiopian and lower-grade material than in Australian opal. Treatment status should be disclosed — confirm before buying if it isn't specified.