Oval cabochon of Oregon (USA) fire opal, 14×10 mm. Translucent caramel-amber tone orange with a depth effect when light passes through it.
Item details
| Mineral |
Fire Opal (SiO₂·nH₂O, hydrated opal) |
| Dimensions |
14×10 mm, approx. height 4–5 mm. Variation of ±0.2 mm. |
| Shape and Back |
Oval, flat back |
| Finish |
Mirror polish |
| Hardness |
5.5–6 Mohs — we recommend a closed bezel setting to protect the edge |
| Origin |
Oregon, USA |
| Treatment |
Untreated |
| Type of piece |
Unique piece |
This specific piece
Oregon fire opal is a body color orange opal — its value lies in the translucency and warmth of the caramel-amber tone, not in the iridescent play-of-color of precious opal. When placed over a light source, the color intensifies from within: the gem seems to contain light inside. This backlighting effect is real and permanent — it is a direct consequence of the material's translucency, not of any treatment.
How fire opal is formed
Fire opal is hydrated silica (SiO₂·nH₂O) with an amorphous structure — without an ordered crystal lattice, unlike crystalline minerals. The orange color comes from traces of iron oxides incorporated during deposition in volcanic cavities. The Oregon and Idaho deposits are formed in rhyolite flows and volcanic tuffs where gelatinous silica circulated through cracks for millions of years before solidifying.
What setting it works for
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Bezel setting (925 silver) — recommended due to opal's moderate hardness (5.5–6 Mohs). The bezel protects the perimeter from impacts. An oxidized or matte silver bezel contrasts particularly well with the orange of the opal.
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Central pendant — the 14×10 mm has the ideal presence for a single-gem pendant; the translucent orange captures and enhances ambient light.
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Wire wrap — the mirror surface of the cabochon allows the wire to slide easily without marking the gem; a bare silver or copper wire wrap complements the opal's orange tone.
Fire opal in lapidary tradition
The most historically known fire opal comes from Mexico — particularly Querétaro and Jalisco — where the Aztecs called it vitzitziltecpal (hummingbird stone) for its fiery tones. The Oregon and Idaho deposits are North American sources commercially exploited since the 20th century that produce material with the same type of orange-amber translucency as the Mexican deposits. Fire opal entered Western Victorian jewelry in the late 19th century when European travelers brought it from Mexico as a captured fire stone.
In crystal tradition, fire opal is associated with vitality and creative energy. The symbolic properties attributed to minerals belong to cultural and historical traditions. They are shared for educational purposes, not as medical advice or a substitute for professional care.
How to recognize genuine fire opal
Genuine fire opal has an orange that intensifies with backlighting — a "trapped light" effect that dyed glass does not reproduce with the same depth or warmth. Opal is notably lighter than glass of the same size (specific gravity 1.98–2.25 vs glass 2.5). Under magnification, the interior may show curvilinear micro-fissures typical of hydrated silica (crazing), which are natural structures, not damage.
Frequently asked questions
Does this opal have play-of-color?
No. This is body color fire opal — translucent orange without the iridescent multicolored effect that defines precious opal.
What jewelry is it most suitable for?
Pendants that allow the gem to be seen from different angles to take advantage of the backlighting effect. Also occasional-wear rings with a bezel setting.
Does it have any treatment?
Untreated. The orange color is natural — a consequence of iron oxides in the hydrated silica.
Why is it a unique piece?
The exact tone, the distribution of translucency, and the internal morphology are specific to each opal nodule. No two pieces are identical, even from the same deposit.
See also: cabochon collection · silversmithing · wire wrap.
