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Brahegatan 10
BOX 5038
114 37 Stockholm
All auctions / Ethnographic / Opal Rough- 11 g - (6)
Lotto consisting of 6 Rough Ethiopian Opals 55 Carats - 11Gr Following is the description for single lots 1) LOTTO 1 RAW OPAL 2gr-10Carati The stone shown in the photo is a rough Ethiopian fire opal (also known as Welo Opal). Description and Physical Characteristics * Morphology and Cut: This is a mineral crystal in rough state (un-cut and unpolished), retaining its original free form (rough). The top part still shows a portion of the clay/yellowish matrix rock color. * Color and Transparency: The base body of the stone has a warm honey-orange translucent tone. The most important feature is the optical phenomenon visible at the center: a sharp iridescent flash of neon green and yellowish color caused by light diffraction inside the silica lattice of the stone. * Weight Conversion: The 2 grams indicated correspond exactly to 10 carats (ct), the standard unit of measure used in the gem market. Lot 2 rough opal 4Gr - 20 Carats This specimen is a fragment of noble rough opal on a rocky matrix (Boulder Opal), presumably of Australian origin. The value of this piece is higher than the previous ones due to the doubled weight (4g equals 20 carats) and the presence of rarer colors (purple/violet increases value compared to just green). Description and Visual Characteristics * Morphology and Structure: It is a natural rough specimen. The gem is set within a heavy host rock (matrix) of dark brown, clayey and ferruginous color. * Play-of-Color: Compared to the previous photo of the same piece, this closer and better-lit shot shows greater potential. On the upper-right portion there is a vivid iridescent flash of neon green and purple/violet. * The Body of the Opal: The central vein running through the rock has a milky and semi-glossy texture, with gray-blue zones that serve as the base for the surface iridescence. Description and Visual Characteristics * Morphology and Structure: It is a natural rough specimen. The gem is set within a heavy host rock (matrix) of dark brown, clayey and ferruginous color. * Play-of-Color: Compared to the previous photo of the same piece, this closer and better-lit shot shows greater potential. On the upper-right portion there is a vivid iridescent flash of neon green and purple/violet. * The Body of the Opal: The central vein crossing the rock has a milky and semi-glossy texture, with gray-blue areas that form the base for surface iridescence. Lot 3 Rough Opal 2Gr 10 Ct. This specimen is an exceptional fragment of noble hydro-precious fire opal rough, of Ethiopian origin (Welo). It is the highest quality piece among those shown so far. Gemmological Description and Features * Play-of-Color: The stone shows a complete and vivid spectrum. Under this direct light, intense multicolored iridescent flashes are clearly visible: fire red, neon orange, bright green and blue specks in the lower part. * Body Tone: The opal body has a highly translucent crystal base with amber and honey tones, typical of African fire opals with a glassy texture. * Matrix Presence: The grayish porous host rock is confined almost entirely to the right edge and bottom. This means that nearly all the weight is noble opal usable material. * Size/Weight Ratio: 2 grams equals 10 carats (ct). The measurements (1.8 cm height and less than 1 cm thick and wide) indicate an elongated shard form. Lot 4 Rough Opal 1Gr - 5 Ct. This specimen is a fragment of white crystal rough noble opal (most likely a Welo Opal of Ethiopian origin). Gemmological Description and Features * Play-of-Color: The stone shows a beautiful color contrast. Intense neon electric greens appear as spots across the surface, accompanied by a distinct and valuable orange/red patch on the left side and yellow reflections on the right. * Body Tone: Unlike the previous pieces with an amber base, this sample has a milky and semi-glossy base, defined in gemology as white opal or clear crystal opal. * Structure and Matrix: The piece is in rough natural state. It features a portion of sandy beige host rock confined to the back and upper-right edge, while the main body is entirely composed of noble opal. * Size/Weight: 1 gram equals exactly 5 carats (ct). The dimensions indicate a compact and slightly arched shard. Lot 5 Opal -1 Gr. 5Ct. This specimen is a small shard of crystal rough noble opal (Welo type, Ethiopian origin). 1 gram (5 carats). Gemmological Description and Features * Play-of-Color: Despite the small size, the stone shows a beautiful concentrated iridescence. A vivid shifting neon green flash stands out in the lower part, accompanied by electric blue specks and orange hues over the honey-toned base. * Body Tone: The base has a glassy, translucent, and crystalline (crystal opal) texture ranging from transparent to light amber-yellow at the center of the fragment. * Structure and Matrix: The piece is entirely rough natural. On the upper left edge there is a small crust of dark brown host rock, while the right portion ends in a very thin and transparent pointed form. * Size/Weight: The weight of 1 gram equals exactly 5 carats (ct). The shape is very irregular, jagged, and shard-like. Market Value Analysis The price is slightly lower than the preceding 1-gram piece due to its geometry: * Jagged Shape: The thin shard structure and the presence of sharp edges limit workability. A possible cabochon cut would entail a very high material loss, making it ideal mainly as a raw or educational collection piece. * Vivid Green-Blue: The color quality remains very high; blue and green reflections are saturated and react well even in suboptimal lighting, keeping the piece interesting for mineral enthusiasts. Lot 6 Opal 5 Ct This specimen is a fragment of noble crystal opal rough on matrix, clearly of Ethiopian origin (Welo). Gemmological Description and Features * Play-of-Color: On the largely glassy base there are delicate but widespread iridescent spots. A blue electric speck is notable in the lower part and subtle orange and green reflections in the central section. * Body Tone: The opal body is of transparent crystal opal type, almost colorless and ice-like, different from the previous pieces with a more amber base. * Matrix and Structure: The ferruginous dark brown host rock is concentrated at the top, forming a clear cap above the crystal. The structure shows several natural fractures and internal cleavage lines typical of rough material extracted by breaking. * Proportions: The weight of 1 gram (5 carats) is developed on a nearly cubic and compact shape, given the nearly identical measurements of width (1.03 cm), height (1 cm) and depth (9 mm). Total Lot of 6 Ethiopian Opals - 11 grams - total 55 Carats A total weight of 11 grams of Ethiopian opals corresponds exactly to 55 carats. The overall commercial value for this entire rough lot ranges from 170 to 310 euros, calculated by summing the individual pieces examined so far and considering the value premium of the higher-quality pieces with red and orange reflections. Inspect the images for proper evaluation. Shipped with protective packaging and tracking
Estimate:$204.13
To the auctionView all items fromCatawikiorEthnographic
Estimate:
$204.13
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