*Complimentary Specimens** As a gesture of appreciation, winning lots with a final hammer price above €50 will include one small additional mineral offered entirely free of charge. —————— Description: What could be rarer than a vivid yellow cubic crystal or a perfectly rounded fancy stone shaped by time and transport? A triangular natural diamond whose very surface is engraved with the geometry of its own formation. This is not merely a diamond crystal. It is a crystallographic manuscript, written in carbon, where miniature triangles echo the greater triangular face that contains them. This exceptional natural diamond presents a sharply defined triangular morphology derived from an original octahedral growth habit. One dominant octahedral face forms the principal surface, rising with precise angular definition and tapering into a refined apex. The overall geometry is neither rolled nor heavily resorbed, but structurally preserved, allowing the crystal’s internal symmetry to remain legible to the eye. Across this triangular face lies the feature that elevates the specimen into a distinct mineralogical category: well developed trigons. These microscopic to visible triangular etch structures are not inclusions, nor surface damage, but natural dissolution features formed deep within the mantle and during kimberlitic ascent. Each trigon mirrors the symmetry of the diamond’s cubic lattice, appearing as inverted or upright miniature triangles that repeat across the face in ordered alignment. Their presence confirms the crystal’s authenticity and its exposure to mantle metasomatic processes. They are, in essence, the fingerprint of geological time. Under direct illumination, the diamond displays a refined grey to near colourless body tone with a cool internal translucency. The grey nuance is subtle and intrinsic, generated by minor lattice distortions and structural irregularities within the carbon framework. Under backlighting, the crystal reveals increased transparency, and the trigons become even more pronounced, casting delicate internal reflections and reinforcing the depth of the surface relief. The lustre is distinctly adamantine. Even without polishing, light reflects sharply from the planar octahedral surfaces, producing crisp flashes that contrast with the matte micro relief of the etched trigons. This interaction between smooth crystallographic planes and microscopic dissolution structures creates a dynamic optical behaviour rarely observed in more rounded or heavily resorbed specimens. The crystal presents as a thin octahedral fragment or slice preserving one dominant face. Its reduced thickness enhances light transmission, allowing internal structure and surface etching to remain clearly visible without optical obstruction. Recovered from the diamond rich province of Lunda Norte, Angola, this specimen is consistent with alluvial diamonds from the region, known for preserving original crystal morphology and crystallographic features. Unlike rounded stones shaped by extended river transport, this piece retains the structural clarity of its octahedral origin. This is a diamond defined not by colour saturation, but by crystallography. By symmetry. By the visible dialogue between growth and dissolution written across its surface. Specifications: • Weight: 0.03 g • Weight in carats: 0.15 ct • Dimensions: 5 × 4 × 0.5 mm • Origin: Lunda Norte, Angola • Gem material: Natural diamond • Crystal system: Cubic • Crystal habit: Octahedral fragment with dominant triangular face • Morphology: Thin triangular plate derived from octahedral growth • Surface structures: Well developed trigons on octahedral face • Colour: Grey to near colourless • Colour distribution: Subtle and internally consistent • Transparency: Translucent to partially transparent under backlight • Lustre: Adamantine • Surface condition: Natural, unpolished, untreated • Alteration: None Notable Points: • Prominent trigons across the octahedral face The triangular etch features are natural dissolution structures aligned with the diamond’s cubic symmetry. Their presence confirms mantle level chemical interaction and significantly enhances mineralogical value compared to smooth surfaced crystals. • Clearly preserved triangular morphology The dominant octahedral face forms a precise geometric triangle, offering a strong visual representation of diamond’s crystallographic identity rather than a mechanically rounded form. • Authentic mantle dissolution signature Trigons form through selective atomic scale dissolution under high temperature conditions. Their ordered repetition reflects internal lattice structure, making this specimen scientifically expressive. • Adamantine lustre on raw surfaces Despite the absence of polishing, the crystal reflects light sharply, demonstrating diamond’s inherent optical strength and refractive power. • Enhanced visibility under backlighting Backlit illumination reveals increased translucency and accentuates trigonal relief, providing educational and display value. • Thin plate morphology The 0.5 mm thickness allows light to penetrate the crystal more readily, enhancing internal visibility without sacrificing structural clarity. • Distinct from rounded alluvial stones Unlike heavily transported diamonds that lose crystallographic definition, this piece retains angular geometry and surface structures, increasing collector appeal. • Consistent with Angolan alluvial origin Morphology and preservation are characteristic of Lunda Norte material, a historically significant diamond producing region. • No mechanical intervention No signs of cutting, polishing, or artificial modification. All structures are naturally formed. • Mineralogical teaching specimen quality The combination of triangular morphology and visible trigons makes this an excellent crystallographic reference example. Collector’s Interest: Diamonds displaying clearly visible trigons are highly sought after by advanced collectors because they represent more than aesthetic beauty. They represent geological history made visible. The triangular morphology offers immediate crystallographic clarity, while the trigons confirm mantle level processes that are absent from smoother, more rounded stones. Compared to cubic crystals or rounded alluvial diamonds, trigonal octahedral faces provide a higher degree of structural authenticity and scientific significance. This specimen bridges aesthetic appeal and mineralogical depth, making it suitable both for display and for study within serious natural diamond collections. Lapidary Potential: From a lapidary perspective, the thin plate structure and consistent body tone offer theoretical cutting possibilities. However, any cutting would permanently remove the trigons and destroy the crystallographic features that define this specimen’s uniqueness. Its highest value lies in preservation. As a natural octahedral fragment bearing visible trigons, it represents diamond in one of its most intellectually and geologically compelling forms. ——————- Shipping and Handling: All orders are shipped by Portuguese National Post. • Dispatch time: within 1 to 3 business days after payment confirmation to Catawiki • Transit time with CTT service: between 5 to 7 business days within europe and worldwide, depending on destination national post. • A tracking number is always provided Photography and transparency: All photographs are taken under controlled lighting conditions using a macro lens, carefully selected to present each specimen as accurately as possible. No filters, colour enhancement, or artificial saturation are applied. The lighting setup uses a calibrated 5500K light source, replicating neutral daylight to reveal natural tones, surface features, and internal characteristics. Under warmer or weaker indoor lighting, colours may appear slightly different, which is normal. The purpose of this photographic process is documentation and representation, not visual enhancement. Images are intended to reflect the specimen faithfully as it appears under balanced natural light conditions. Identification and ethics: All specimens offered are natural and described to the best of our knowledge, based on direct sourcing, professional experience, and information provided by trusted suppliers working at the origin. Every effort is made to ensure transparency and accuracy regarding identification, locality, and general characteristics, avoiding misleading statements about treatment, provenance, or nature. Customs and import taxes: Any customs duties, import fees, or local taxes applied by the destination country are entirely the responsibility of the winning bidder. These charges are not included in the auction price or shipping cost and are determined by the buyer’s local authorities. Guarantee and resolution: Customer satisfaction is important. In the unlikely event of an issue such as loss, damage, or discrepancy, please contact us promptly through Catawiki’s messaging system. Each case is handled individually and fairly, with appropriate solutions offered when justified. Appreciation and commitment: We sincerely thank you for your trust. Our work focuses on careful selection, accurate representation, and respectful presentation of mineral specimens with character and interest. Each piece is chosen for its individual qualities rather than speculative or financial considerations. We aim to provide a transparent, reliable, and consistent experience for collectors at all levels. With gratitude, GemPulse Minerals