Pictures are unedited and accurately describe the Opal The certificate states: Antwerp Laboratory for Gemstone Testing report no. 97213882 Date: 28 July 2025 Stone details: Identification: Natural opal Variety: Crystal opal Shape / cutting style: Oval cabochon Measurements: 16.00 × 12.84 × 9.51 mm Weight: 10.66 ct Grading details: Color: White (yellowish) + play of colors Transparency: Transparent Optical effect: Opalescence Origin opinion: Ethiopia Comments: No indications of treatment This is a large Ethiopian crystal opal cabochon, with transparent body and play-of-color, commercially positioned as a statement gemstone for rings, pendants, or collector pieces. The size above 10 carats gives it strong visual presence, while Ethiopian origin is a recognized commercial source for crystal opal. Certified natural crystal opal weighing 10.66 carats, expertly fashioned as a substantial oval cabochon and accompanied by Antwerp Laboratory for Gemstone Testing certification confirming natural opal identity, crystal opal variety, Ethiopian origin, and untreated status. Measuring approximately 16.00 × 12.84 × 9.51 mm, this impressive gemstone offers notable size, strong visual presence, and collector-level individuality, placing it in a category highly sought after by buyers looking for exceptional natural opals with both gemological documentation and distinctive optical performance. The stone displays a transparent crystal body with soft white to slightly yellowish base tone, allowing light to penetrate deeply through the gem and activate vivid internal color play across multiple layers. Particularly striking are strong flashes of red, orange, blue, and green, appearing dynamically across the surface and within the body depending on viewing angle and light source. These intense spectral reactions create constant movement inside the gem, giving the stone a living character highly valued in premium crystal opals. Red and orange flashes are especially important in the opal market because stronger warm-color fire is considered among the most commercially desirable optical features, while blue and green provide contrast, depth, and full-spectrum visual richness. This natural Ethiopian crystal opal is unique by nature, as no two opals display identical internal patterning, color arrangement, or optical response. The exact combination of transparency, fire distribution, body tone, and internal color architecture makes this gemstone a one-of-a-kind collector stone rather than a standard calibrated jewelry stone. Its individuality is reinforced by the large size above 10 carats, which gives room for broader color fields and stronger visible fire than smaller opals can typically present. The oval cabochon cut has been chosen to maximize optical display, preserving dome height and internal light reflection so that the play-of-color remains vivid from multiple viewing positions. This makes the gemstone exceptionally suitable as a center stone for high-end rings, pendants, statement pieces, luxury bespoke jewelry, or private gem collections where a single natural stone is intended to dominate the design. Untreated natural opals of this size and transparency, especially with documented Ethiopian origin and visible multicolor fire, continue to attract increasing international demand among gemstone investors, specialist dealers, and collectors. The certification explicitly notes no indications of treatment, which is a major selling factor in today’s market, as untreated opals with strong natural fire are considered significantly more desirable than enhanced material. This untreated status supports long-term collectability, stronger resale confidence, and greater market credibility. Ethiopian crystal opals have become one of the most important categories within the fine opal market because of their ability to combine transparency, strong internal fire, and vivid spectral color in larger sizes. Stones that additionally show pronounced red, orange, blue, and green flashes in a clean cabochon with documented laboratory certification are increasingly selected not only for jewelry but also as investment gemstones, particularly when size exceeds ten carats and visual performance remains strong. This gemstone should be viewed not simply as a decorative stone but as a special natural investment piece: rare in appearance, unique in optical character, untreated, certified, and immediately suitable for both high-end jewelry creation and long-term gemstone holding. Large certified opals with this level of visual fire are increasingly appreciated by collectors because they combine beauty, rarity, and individuality in a single natural object. A unique certified untreated Ethiopian crystal opal with strong red, orange, blue, and green play-of-color, transparent crystal body, large 10.66 carat size, collector-grade visual impact, and exceptional individuality—well suited for luxury jewelry, serious gemstone collecting, private investment, and premium resale within the international natural opal market. Assuming a stronger premium positioning and pricing it as a top visual Ethiopian crystal opal rather than standard certified material, the value can be argued higher because the photos show several characteristics associated with upper retail inventory: dominant broad red fire saturated orange bands vivid neon green fields visible blue and violet secondary flashes full-face color movement across multiple angles large dome with strong internal depth untreated status clean, highly presentable face for a crystal opal of this size At 10.66 ct, once a crystal opal consistently shows strong red over multiple orientations, pricing often moves out of ordinary wholesale brackets and into premium collector retail. A more aggressive commercial estimate: Premium wholesale replacement level: €800–1,200 Specialist retail asking price: €1,500–2,500 Collector-facing retail with strong presentation: €2,500–3,500 Exceptional private buyer if marketed as unique untreated investment opal: up to €4,000 possible Why a higher number can be justified: red remains the highest-value color in opal the stone is not dependent on one single flash zone; color appears repeatedly transparency plus broad fire is stronger than average Ethiopian crystal material untreated certification supports premium positioning above 10 ct with attractive proportions gives collector weight In premium retail language, this is no longer just a decorative opal but a large untreated multicolor crystal opal with collector-grade face appeal and investment-grade visual rarity. A realistic strong asking price today: €2,800 A realistic strong selling range: €1,800–2,400 If placed in the right venue with excellent video: €3,000+ is defendable The key is that this must be sold as a unique large untreated Ethiopian crystal opal with dominant red fire, not simply as “opal 10.66 ct”. If useful, I can also explain whether this stone could pass **€5,000 in a high-end market if recertified by Swiss Gemmological Institute SSEF or Gübelin Gem Lab.