Opal Rough- 11 g - (6)
Starting bid
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Expert
Selected by Antonio Rapisarda
Holds a master’s in chemistry with 25 years’ experience in minerals consulting.
Estimate € 220 - € 250
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Description from the seller
Lot consisting of 6 Rough Ethiopian Opals
55 Carats - 11g
Followed by description for single lots
1) LOT 1 ROUGH OPAL 2g - 10 Carats
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 the rough state (un-cut and unpolished), preserving its original free form (rough). The upper part still shows a portion of the clay/gipsy-colored matrix rock in a light hue.
* Color and Transparency: The base body of the stone has a warm orange-honey tone, translucent. The most important feature is the optical phenomenon at the center: a sharp iridescent flash of neon green and yellow generated by light diffraction inside the silica lattice of the stone.
* Weight Conversion: The indicated 2 grams exactly correspond to 10 carats (ct), the standard market unit used in gemstones.
Lot 2 rough opal 4Gr - 20 Carats
This specimen is a rough noble opal fragment on a rocky matrix (Boulder Opal), presumably of Australian origin.
The value of this piece is higher than the previous due to the doubled weight (4g equals 20 carats) and the presence of rarer colors (purple/violet enhances value compared to only green).
Visual Description and Characteristics
* Morphology and Structure: It is a natural rough specimen. The gem is embedded within a heavy brown, clayey and ferruginous mother rock (matrix).
* Play-of-Color: Compared to the previous photo of the same piece, this closer, better-lit shot shows higher potential. In the upper-right portion stands a vivid iridescent flash of neon green and purple/violet.
* The Body of Opal: The central vein running through the rock has a milky and semi-glossy texture, with gray-blue zones that serve as a base for surface iridescence.
Description and Visual Characteristics
* Morphology and Structure: It is a natural rough sample. The gem is set within a heavy dark brown, clay-rich, ferruginous matrix.
* Play-of-Color: Compared to the previous photo of the same piece, this closer, better-lit shot shows higher potential. In the upper-right portion stands a vivid iridescent flash of neon green and purple/violet.
* The Body of Opal: The central vein across the rock has a milky and semi-glossy texture, with gray-blue zones forming the base for surface iridescence.
Lot 3 Rough Opal 2Gr 10 Ct.
This specimen is an exceptional fragment of noble hydro-opaque fire opal rough, of Ethiopian origin (Welo).
It is the piece of highest quality among those shown so far.
Gemmological Description and Characteristics
* Play-of-Color: The stone displays a complete and vivid spectrum. Under this direct lighting, intense multicolored iridescent flashes are clearly visible: fire red, neon orange, bright green, and blue specks at the bottom.
* Body Tone: The opal body has a highly translucent crystalline base with amber and honey tones, typical of African fire opals with a glassy texture.
* Matrix Presence: The grayish porous mother rock is confined almost entirely to the right edge and bottom. This means almost all the weight is noble opal usable for cutting.
* 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 shape.
Lot 4 Rough Opal 1Gr - 5 Ct.
This specimen is a fragment of white crystal rough noble opal (very likely a Welo Opal of Ethiopian origin).
Gemmological Description and Characteristics
* Play-of-Color: The stone shows a beautiful color contrast. Notable electric neon green flashes distributed as patches across the surface, accompanied by a distinct orange/red patch on the left side and yellow reflections on the right.
* Body Tone: Unlike the previous pieces with amber base, this sample has a milky translucent base, defined in gemology as white opal or clear crystal.
* Structure and Matrix: The piece is in its natural rough state. It features a portion of sandy beige mother rock confined to the back and upper-right edge, while the main body is composed entirely of noble opal.
* Size/Weight: 1 gram corresponds exactly to 5 carats (ct). The dimensions indicate a compact, slightly curved shard.
Lot 5 Opal -1 Gr. 5Ct.
This specimen is a small shard of crystalline noble opal rough (Welo-type, Ethiopian origin). 1 gram (5 carats).
Gemmological Description and Characteristics
* Play-of-Color: Despite the small size, the stone shows a beautiful iridescence concentrated. A vivid, shifting neon green flash at the bottom, accompanied by blue electric specks and orange hues over a honeyed base.
* Body Tone: The base has a glassy, translucent, crystalline texture (crystal opal) varying from transparent to light amber yellow at the center of the fragment.
* Structure and Matrix: The piece is entirely natural rough. On the upper left edge, a small crust of brownish dark mother rock is visible, while the right portion ends in a very thin, transparent pointed shape.
* Size/Weight: The weight of 1 gram equals exactly 5 carats (ct). The form is very irregular, jagged, and shard-like.
Market Value Analysis
The price is slightly lower than the previous 1-gram piece due to its geometry:
* Jagged Shape: The shard-like structure and the presence of sharp edges limit workability. Any cabochon-cut would result in a very high material loss, making it ideal mainly as a rough or educational collector piece.
* Brightness of Green-Blue: The color quality remains very high; blue and green reflections are saturated and respond well even in suboptimal lighting, keeping the piece interesting for mineral enthusiasts.
Lot 6 Opal 5 Ct
This specimen is a fragment of noble crystalline opal rough on matrix, clearly of Ethiopian origin (Welo).
Gemmological Description and Characteristics
* Play-of-Color: On the predominantly glassy base, delicate but widespread iridescent spots are visible. A blue electric speck at the bottom and light orange and green reflections in the central section stand out.
* Body Tone: The opal body is a transparent crystal opal, almost colorless and ice-like, different from the previous pieces with a more amber background.
* Matrix and Structure: The ferruginous dark brown mother rock is concentrated at the top vertex, creating a clear cap above the crystal. The structure shows several natural fractures and internal splitting lines typical of rough material extracted by breakage.
* Proportions: The 1-gram weight (5 carats) develops on a nearly cubic and compact form, given the almost identical dimensions: width 1.03 cm, height 1 cm, and depth 9 mm.
Total Lot of the 6 Ethiopian Opals - 11 grams - total 55 Carats
An overall weight of 11 grams of Ethiopian opals corresponds exactly to 55 carats.
The total commercial value for this entire rough lot is estimated between 170 and 310 euros, calculated by summing the individual pieces examined so far and considering the value premium of higher-quality pieces with red and orange reflections.
Look at the images for proper evaluation.
Shipped with protective packaging and tracking
Lot consisting of 6 Rough Ethiopian Opals
55 Carats - 11g
Followed by description for single lots
1) LOT 1 ROUGH OPAL 2g - 10 Carats
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 the rough state (un-cut and unpolished), preserving its original free form (rough). The upper part still shows a portion of the clay/gipsy-colored matrix rock in a light hue.
* Color and Transparency: The base body of the stone has a warm orange-honey tone, translucent. The most important feature is the optical phenomenon at the center: a sharp iridescent flash of neon green and yellow generated by light diffraction inside the silica lattice of the stone.
* Weight Conversion: The indicated 2 grams exactly correspond to 10 carats (ct), the standard market unit used in gemstones.
Lot 2 rough opal 4Gr - 20 Carats
This specimen is a rough noble opal fragment on a rocky matrix (Boulder Opal), presumably of Australian origin.
The value of this piece is higher than the previous due to the doubled weight (4g equals 20 carats) and the presence of rarer colors (purple/violet enhances value compared to only green).
Visual Description and Characteristics
* Morphology and Structure: It is a natural rough specimen. The gem is embedded within a heavy brown, clayey and ferruginous mother rock (matrix).
* Play-of-Color: Compared to the previous photo of the same piece, this closer, better-lit shot shows higher potential. In the upper-right portion stands a vivid iridescent flash of neon green and purple/violet.
* The Body of Opal: The central vein running through the rock has a milky and semi-glossy texture, with gray-blue zones that serve as a base for surface iridescence.
Description and Visual Characteristics
* Morphology and Structure: It is a natural rough sample. The gem is set within a heavy dark brown, clay-rich, ferruginous matrix.
* Play-of-Color: Compared to the previous photo of the same piece, this closer, better-lit shot shows higher potential. In the upper-right portion stands a vivid iridescent flash of neon green and purple/violet.
* The Body of Opal: The central vein across the rock has a milky and semi-glossy texture, with gray-blue zones forming the base for surface iridescence.
Lot 3 Rough Opal 2Gr 10 Ct.
This specimen is an exceptional fragment of noble hydro-opaque fire opal rough, of Ethiopian origin (Welo).
It is the piece of highest quality among those shown so far.
Gemmological Description and Characteristics
* Play-of-Color: The stone displays a complete and vivid spectrum. Under this direct lighting, intense multicolored iridescent flashes are clearly visible: fire red, neon orange, bright green, and blue specks at the bottom.
* Body Tone: The opal body has a highly translucent crystalline base with amber and honey tones, typical of African fire opals with a glassy texture.
* Matrix Presence: The grayish porous mother rock is confined almost entirely to the right edge and bottom. This means almost all the weight is noble opal usable for cutting.
* 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 shape.
Lot 4 Rough Opal 1Gr - 5 Ct.
This specimen is a fragment of white crystal rough noble opal (very likely a Welo Opal of Ethiopian origin).
Gemmological Description and Characteristics
* Play-of-Color: The stone shows a beautiful color contrast. Notable electric neon green flashes distributed as patches across the surface, accompanied by a distinct orange/red patch on the left side and yellow reflections on the right.
* Body Tone: Unlike the previous pieces with amber base, this sample has a milky translucent base, defined in gemology as white opal or clear crystal.
* Structure and Matrix: The piece is in its natural rough state. It features a portion of sandy beige mother rock confined to the back and upper-right edge, while the main body is composed entirely of noble opal.
* Size/Weight: 1 gram corresponds exactly to 5 carats (ct). The dimensions indicate a compact, slightly curved shard.
Lot 5 Opal -1 Gr. 5Ct.
This specimen is a small shard of crystalline noble opal rough (Welo-type, Ethiopian origin). 1 gram (5 carats).
Gemmological Description and Characteristics
* Play-of-Color: Despite the small size, the stone shows a beautiful iridescence concentrated. A vivid, shifting neon green flash at the bottom, accompanied by blue electric specks and orange hues over a honeyed base.
* Body Tone: The base has a glassy, translucent, crystalline texture (crystal opal) varying from transparent to light amber yellow at the center of the fragment.
* Structure and Matrix: The piece is entirely natural rough. On the upper left edge, a small crust of brownish dark mother rock is visible, while the right portion ends in a very thin, transparent pointed shape.
* Size/Weight: The weight of 1 gram equals exactly 5 carats (ct). The form is very irregular, jagged, and shard-like.
Market Value Analysis
The price is slightly lower than the previous 1-gram piece due to its geometry:
* Jagged Shape: The shard-like structure and the presence of sharp edges limit workability. Any cabochon-cut would result in a very high material loss, making it ideal mainly as a rough or educational collector piece.
* Brightness of Green-Blue: The color quality remains very high; blue and green reflections are saturated and respond well even in suboptimal lighting, keeping the piece interesting for mineral enthusiasts.
Lot 6 Opal 5 Ct
This specimen is a fragment of noble crystalline opal rough on matrix, clearly of Ethiopian origin (Welo).
Gemmological Description and Characteristics
* Play-of-Color: On the predominantly glassy base, delicate but widespread iridescent spots are visible. A blue electric speck at the bottom and light orange and green reflections in the central section stand out.
* Body Tone: The opal body is a transparent crystal opal, almost colorless and ice-like, different from the previous pieces with a more amber background.
* Matrix and Structure: The ferruginous dark brown mother rock is concentrated at the top vertex, creating a clear cap above the crystal. The structure shows several natural fractures and internal splitting lines typical of rough material extracted by breakage.
* Proportions: The 1-gram weight (5 carats) develops on a nearly cubic and compact form, given the almost identical dimensions: width 1.03 cm, height 1 cm, and depth 9 mm.
Total Lot of the 6 Ethiopian Opals - 11 grams - total 55 Carats
An overall weight of 11 grams of Ethiopian opals corresponds exactly to 55 carats.
The total commercial value for this entire rough lot is estimated between 170 and 310 euros, calculated by summing the individual pieces examined so far and considering the value premium of higher-quality pieces with red and orange reflections.
Look at the images for proper evaluation.
Shipped with protective packaging and tracking
Details
Number of objects
6
Main mineral
Opal
Mineral form
Rough
Supplement
55 carats
Weight
11 g
Origin (region/city)
Italy
Country of origin
Ethiopia
Sold by
Disclaimer
It is believed that certain gemstones and minerals have beneficial health and spiritual properties. However, using or wearing gemstones or minerals does not mean that you can treat, cure or prevent any disease. Please consult your health care professional for information on health care issues and do not stop any medications or courses of treatment, without first consulting your health care professional. The use of gemstones or minerals as a wellness therapy is one of personal choice. While stones or crystals have been used historically to relieve or prevent symptoms, the objects sold on our website offer no guarantee of results. Therefore, Catawiki cannot guarantee or be held liable for the effectiveness of these objects sold herein.
It is believed that certain gemstones and minerals have beneficial health and spiritual properties. However, using or wearing gemstones or minerals does not mean that you can treat, cure or prevent any disease. Please consult your health care professional for information on health care issues and do not stop any medications or courses of treatment, without first consulting your health care professional. The use of gemstones or minerals as a wellness therapy is one of personal choice. While stones or crystals have been used historically to relieve or prevent symptoms, the objects sold on our website offer no guarantee of results. Therefore, Catawiki cannot guarantee or be held liable for the effectiveness of these objects sold herein.
