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Gem Inclusion Pairs • Hyperion Siamese Twins

Gem Inclusion Pairs • Hyperion Siamese Twins

Why should Hugh Hefner be the only one to enjoy twins? This special Hyperion Inclusion Gallery features images from the Lotus Gemology Hyperion Inclusion Database, but are shown as pairs, all the better to compare one form of beauty with another.

It would be both an identical work of art only by virtue of its difference.
The same but different, he suggested, like twins.
Johnny Rich, The Human Script

Click on any photo for a larger image.

The first step of preparing a piece of jadeite jade for polymer impregnation is to boil it in acid to remove any mineral impurities from the tiny fissures between the individual crystal grains that make up the jade rock. These fissures are then filled with a polymer. Thus the treatment removes brown discoloration and greatly improves the translucency. However the telltale micro-fissures from the bleaching process can still be seen by examining the surface with overhead light, as shown here. Polymer-impregnated jade is termed “B-jade” in the trade. Untreated jade is known as “A-jade,” while dyed jade is “C-jade.” If a dyed polymer is used, it is termed “B+C jade.” Field of View = 12 mm. In constrast to the B-jade, the surface of this high-quality untreated jadeite jade from Myanmar shows virtually no fissures and slight undercutting from one mineral grain to the next (jadeite is a rock composed of many small crystals). Field of View = 10 mm.

Left: The first step of preparing a piece of jadeite jade for polymer impregnation is to boil it in acid to remove any mineral impurities from the tiny fissures between the individual crystal grains that make up the jade rock. These fissures are then filled with a polymer. Thus the treatment removes brown discoloration and greatly improves the translucency. However the telltale micro-fissures from the bleaching process can still be seen by examining the surface with overhead light, as shown here. Polymer-impregnated jade is termed “B-jade” in the trade. Untreated jade is known as “A-jade,” while dyed jade is “C-jade.” If a dyed polymer is used, it is termed “B+C jade.” Field of View = 12 mm.
Right: In constrast to the B-jade, the surface of this high-quality untreated jadeite jade from Myanmar shows virtually no fissures and slight undercutting from one mineral grain to the next (jadeite is a rock composed of many small crystals). Specimen courtesy of Kiarttichatra Intarungsee. Field of View = 10 mm. Photos: Richard W. Hughes
These included hexagonal crystals in a Sri Lankan sapphire have inclusions of their own. These are actually sapphire crystals captured in a sapphire host, as shown by their extremely low relief. Because of the low relief, the outlines of the crystals are difficult to discern. In darkfield (left) they are hard to distinguish from the surrounding corundum, but in crossed polars (right) it’s apparent that they are distinct crystals of their own.

Left: These included hexagonal crystals in a Sri Lankan blue sapphire have inclusions of their own. These are actually sapphire crystals captured in a sapphire host, as shown by their extremely low relief. Because of the low relief, the outlines of the crystals are difficult to discern.
Right: In darkfield (left) they are hard to distinguish from the surrounding corundum, but in crossed polars (right) it’s apparent that they are distinct crystals of their own. Photos: E. Billie Hughes
Another example of sapphire in a Ceylon sapphire. In darkfield the outline of the sapphire crystal is hard to discern. Switching to crossed polars illuminates the sapphire inclusion dramatically.

Left: Another example of sapphire crystal included in a Ceylon sapphire, this time a yellow sapphire. In darkfield the outline of the sapphire crystal is hard to discern.
Right: Switching to crossed polars illuminates the sapphire inclusion dramatically. Photos: Richard W. Hughes
When viewed in transmitted light, this negative crystal within an untreated Sri Lanka padparadscha displays a hexagonal plate of graphite, along with a needle of diaspore. The undamaged nature of the negative crystal and diaspore needle confirms that the gem has not been heat treated. Using overhead reflected light on the same negative crystal, one can see the high-relief of the hexagonal plate of graphite. The diaspore needle has a refractive index quite close to the surrounding corundum, and so "disappears" into the corundum matrix. The undamaged nature of the negative crystal and diaspore needle confirms that the gem has not been heat treated.

Left: When viewed in transmitted light, this negative crystal within an untreated Sri Lanka padparadscha displays a hexagonal plate of graphite, along with a needle of diaspore. The undamaged nature of the negative crystal and diaspore needle confirms that the gem has not been heat treated.
Right: Using overhead reflected light on the same negative crystal, one can see the high-relief of the hexagonal plate of graphite. The diaspore needle has a refractive index quite close to the surrounding corundum, and so "disappears" into the corundum matrix. The undamaged nature of the negative crystal and diaspore needle confirms that the gem has not been heat treated. Photos: Richard W. Hughes
This red spinel from Tanzania’s Mahenge mines showed an unusual orange coloration surrounding a fingerprint inclusion. When examined in oblique fiber-optic lighting, the orange area displays milky bluish clouds. This unmasks the orange color as a function of scattering, the same phenomena that creates a blue sky and orange sunset.

Left: This red spinel from Tanzania’s Mahenge mines showed an unusual orange coloration surrounding a fingerprint inclusion.
Right: When examined in oblique fiber-optic lighting, the orange area displays milky bluish clouds. This unmasks the orange color as a function of scattering, the same phenomena that creates a blue sky and orange sunset. Photos: Richard W. Hughes
In this heated and fissure-healed ruby from Myanmar, a surface cavity is filled with glass. The glass can be identified by the gas bubble at the lower part of the cavity. The same cavity when viewed with diffuse over head illumination, which clearly reveals its extent. The glass can be identified by its lower luster.

Left: In this heated and fissure-healed ruby from Myanmar, a surface cavity is filled with glass. The glass can be identified by the gas bubble at the lower part of the cavity. 
Right: The same cavity when viewed with diffuse over head illumination, which clearly reveals its extent. The glass can be identified by its lower luster. Photos: Richard W. Hughes
Demonstrating that the inner world can be as captivating as that outside, this Madagascar sapphire displays a small fingerprint scar with a beguiling moiré pattern. The undamaged nature of this inclusion testifies to the natural, untreated origin of the gem. In this sapphire from Sri Lanka, evidence of high temperature heat treatment can be found in this moiré-patterned fingerprint. The once-lovely lacy pattern of liquid droplets is now besmirched by circular “explosions,” where the pressure from heating caused ruptures in the microscopic negative crystals, thus deflowering Mother Nature’s exquisite work of art.

Left: Demonstrating that the inner world can be as captivating as that outside, this Madagascar sapphire displays a small fingerprint scar with a beguiling moiré pattern. The undamaged nature of this inclusion testifies to the natural, untreated origin of the gem. Photo: E. Billie Hughes
Right: In this sapphire from Sri Lanka, evidence of high temperature heat treatment can be found in this moiré-patterned fingerprint. The once-lovely lacy pattern of liquid droplets is now besmirched by circular “explosions,” where the pressure from heating caused ruptures in the microscopic negative crystals, thus deflowering Mother Nature’s exquisite work of art. Photo: Richard W. Hughes
Many Mozambique rubies contain mica crystals, which are extremely heat sensitive and will be damaged by heat treatment, even at relatively low temperatures (800–1000°C). Unheated Mozambique ruby. After heat treatment, Mozambique rubies with mica crystals will display glassy fissures around the mica, as shown here. Heated Mozambique ruby. Photos: E. Billie Hughes

Left: Many Mozambique rubies contain mica crystals, which are extremely heat sensitive and will be damaged by heat treatment, even at relatively low temperatures (800–1000°C). Unheated Mozambique ruby.
Right: After heat treatment, Mozambique rubies with mica crystals will display glassy fissures around the mica, as shown here. Heated Mozambique ruby. Photos: E. Billie Hughes
Many rubies and sapphires contain shallow fissures on their surfaces. These typically display yellow to orange epigenetic iron oxide stains, as shown here. Unheated Mozambique ruby. When such a stone is heat treated, the stains turn white and bubbly fingerprints begin to appear. Heated Mozambique ruby.

Left: Many rubies and sapphires contain shallow fissures on their surfaces. These typically display yellow to orange epigenetic iron oxide stains, as shown here. Unheated Mozambique ruby.
Right: When such a stone is heat treated, the stains turn white and bubbly fingerprints begin to appear. Heated Mozambique ruby. Photos: Richard W. Hughes
This image clearly illustrates what master photomicrographer John Koivula has termed “chromophore cannibalization.” As a sapphire crystal cools, titanium is drawn out of solid solution to form exsolved rutile silk. This causes the surrounding area to be decolorized, as the titanium is no longer available to produce a blue color. This is a natural process and proof the sapphire has not been subjected to artificial heat treatment. When a rutile-silk containing sapphire is artificially heated, titanium from the rutile dissolves into the surrounding sapphire. Once in solid solution, the titanium reacts with iron, creating a blue color. The result is tiny blue halos surrounding the remnants of the rutile silk, a process dubbed “inkspot internal diffusion” by John Koivula. This partially dissolved silk with blue color concentrations is a clear sign that the sapphire was heated and is the opposite of chromophore cannibalization.

Left: This image clearly illustrates what master photomicrographer John Koivula has termed “chromophore cannibalization.” As titanium is drawn out of solid solution to form exsolved rutile silk, the area in the immediate vicinity is decolorized, losing its blue color. This is a natural process and is the reverse of “internal diffusion,” where heat treatment sends the titanium back into solution, creating blue clouds or “inkspots” around the rutile remnants. Photo: E. Billie Hughes
Right: When a rutile-silk containing sapphire is artificially heated, titanium from the rutile dissolves into the surrounding sapphire. Once in solid solution, the titanium reacts with iron, creating a blue color. The result is tiny blue halos surrounding the remnants of the rutile silk, a process dubbed “inkspot internal diffusion” by John Koivula. This partially dissolved silk with blue color concentrations is a clear sign that the sapphire was heated and is the opposite of chromophore cannibalization. Photo: Richard W. Hughes
In this heated sapphire, one can clearly see “ink spot” internal diffusion, caused when the heat treatment partially dissolves the rutile silk, sending titanium into solid solution. This is a sure sign of high-temperature heat treatment. Check the next photo for the appearance in short-wave ultraviolet light. Using a powerful short-wave ultraviolet light, one can see a chalky fluorescence in the same pattern. It is the colorless, rather than blue areas, that fluoresce.

Left: In this heated sapphire, one can clearly see “ink spot” internal diffusion, caused when the heat treatment partially dissolves the rutile silk, sending titanium into solid solution. This is a sure sign of high-temperature heat treatment. Check the next photo for the appearance in short-wave ultraviolet light. Photo: Richard W. Hughes
Right: Using a powerful short-wave ultraviolet light, one can see a chalky fluorescence in the same pattern. It is the colorless, rather than blue areas, that fluoresce. Photo: E. Billie Hughes
Dark red, high relief crystal of primary rutile; surrounded by halo of fine particles; unheated sapphire, Songea, Tanzania; Darkfield + oblique fiber optic illumination. When a sapphire or ruby containing rutile is heated, titanium bleeds from the rutile into the surrounding corundum (entering into solid solution), creating a blue halo. Heated sapphire (actually Be diffused), Songea, Tanzania; lightfield (white filter). Photos: E. Billie Hughes

Left: Dark red, high relief crystal of primary rutile; surrounded by halo of fine particles; unheated sapphire, Songea, Tanzania; Darkfield + oblique fiber optic illumination.
Right: When a sapphire or ruby containing rutile is heated, titanium bleeds from the rutile into the surrounding corundum (entering into solid solution), creating a blue halo. Heated sapphire (actually Be diffused), Songea, Tanzania; lightfield (white filter). Photos: E. Billie Hughes
Unusual birefringent crystals in a low-relief partially healed fissure in a sapphire treated with high-temperature heat plus modest pressure (HT+P). When tested with Lotus Gemology’s microraman, they proved to be corundum. It is thought that they crystallized during the treatment process. When viewed between crossed polars, the crystals stand out much more clearly.

Left: Unusual birefringent crystals in a low-relief partially healed fissure in a sapphire treated with high-temperature heat plus modest pressure (HT+P). When tested with Lotus Gemology’s microraman, they proved to be corundum. It is thought that they crystallized during the treatment process. FOV 4 mm.
Right: When viewed between crossed polars, the crystals stand out much more clearly. Photos: E. Billie Hughes
Secondary healed fissures in corundum are often filled with carbon dioxide, but usually in liquid form. On occasion we see it in both liquid and gaseous form. This series of four images shows liquid carbon dioxide with a gas bubble (the yellow area). As the heat of the microscope warms the specimen, the gas bubble shrinks and eventually disappears. The critical temperature at which the phase changes is 31.2°C. Solid carbon dioxide is what we know as “dry ice.” The existence of carbon dioxide inclusions in sapphire was first noted by David Brewster in 1826. He also noted the explosive nature of such inclusions, which burst at temperatures generally between 250–400°C. Secondary healed fissures in corundum are often filled with carbon dioxide, but usually in liquid form. On occasion we see it in both liquid and gaseous form. This series of four images shows liquid carbon dioxide with a gas bubble (the yellow area). As the heat of the microscope warms the specimen, the gas bubble shrinks and eventually disappears. The critical temperature at which the phase changes is 31.2°C. Solid carbon dioxide is what we know as “dry ice.” The existence of carbon dioxide inclusions in sapphire was first noted by David Brewster in 1826. He also noted the explosive nature of such inclusions, which burst at temperatures generally between 250–400°C.
Secondary healed fissures in corundum are often filled with carbon dioxide, but usually in liquid form. On occasion we see it in both liquid and gaseous form. This series of four images shows liquid carbon dioxide with a gas bubble (the yellow area). As the heat of the microscope warms the specimen, the gas bubble shrinks and eventually disappears. The critical temperature at which the phase changes is 31.2°C. Solid carbon dioxide is what we know as “dry ice.” The existence of carbon dioxide inclusions in sapphire was first noted by David Brewster in 1826. He also noted the explosive nature of such inclusions, which burst at temperatures generally between 250–400°C. Secondary healed fissures in corundum are often filled with carbon dioxide, but usually in liquid form. On occasion we see it in both liquid and gaseous form. This series of four images shows liquid carbon dioxide with a gas bubble (the yellow area). As the heat of the microscope warms the specimen, the gas bubble shrinks and eventually disappears. The critical temperature at which the phase changes is 31.2°C. Solid carbon dioxide is what we know as “dry ice.” The existence of carbon dioxide inclusions in sapphire was first noted by David Brewster in 1826. He also noted the explosive nature of such inclusions, which burst at temperatures generally between 250–400°C.

From Top Left to Right: Secondary healed fissures in corundum are often filled with carbon dioxide, but usually in liquid form (solid carbon dioxide is what we know as “dry ice”). On occasion we see it in both liquid and gaseous form. This series of four images shows liquid carbon dioxide with a gas bubble (the yellow area). As the heat of the microscope warms the specimen, the gas bubble shrinks and eventually disappears. The critical temperature at which the phase changes is 31.2°C. The existence of carbon dioxide inclusions in sapphire was first noted by David Brewster in 1826. He also noted the explosive nature of such inclusions, which burst at temperatures generally between 250–400°C. Photos: Richard W. Hughes
Many crystals contain shallow fissures on their surfaces. In sapphires from Sri Lanka, Myanmar and Madagascar, these fissures often contain yellow stains (left). High-temperature heating not only destroys the yellow stains, but begins a process of healing, where the fissures turn white and start forming fingerprints, as we can see at right. Photos: Richard W. Hughes Many crystals contain shallow fissures on their surfaces. In sapphires from Sri Lanka, Myanmar and Madagascar, these fissures often contain yellow stains (left). High-temperature heating not only destroys the yellow stains, but begins a process of healing, where the fissures turn white and start forming fingerprints, as we can see at right. Photos: Richard W. Hughes

Left: Many crystals contain shallow fissures on their surfaces. In sapphires from Sri Lanka, Myanmar and Madagascar, these fissures often contain epigenetic yellow stains caused by deposits from Fe-rich fluids. 
Right: High-temperature heating not only destroys the yellow stains, but begins a process of healing, where the fissures turn white and start forming fingerprints, as we can see here. Note that such yellow stains are generally missing in the fissures of Kashmir sapphires. Photos: Richard W. Hughes
Left: Rosette inclusion surrounding a mica crystal in an unheated Mozambique ruby, seen in transmitted. Reflected light reveals surface detail that is masked in transmitted light. Photos: Richard W. Hughes

Left: Rosette inclusion surrounding a mica crystal in an unheated Mozambique ruby, seen in transmitted.
Right: Reflected light reveals surface detail that is masked in transmitted light. Photos: Richard W. Hughes
Overhead lighting was used to photograph this scene in a violet sapphire from Sri Lanka, which shows two large mica plates. The undamaged state of the mica reveals that this sapphire has not been subjected to heat treatment. A combination of dark field and overhead lighting was used to photograph the same scene as at left, revealing two large mica plates and smaller rounded zircon crystals. The undamaged state of the mica reveals that this sapphire has not been subjected to heat treatment.

Left: Overhead lighting was used to photograph this scene in a violet sapphire from Sri Lanka, which shows two large mica plates. The undamaged state of the mica reveals that this sapphire has not been subjected to heat treatment.
Right: A combination of dark field and overhead lighting was used to photograph the same scene as at left, revealing two large mica plates and smaller rounded zircon crystals. The undamaged state of the mica reveals that this sapphire has not been subjected to heat treatment. Photos: Richard W. Hughes
Left: In this flattened negative crystal in a Sri Lankan padparadscha sapphire, multiple phases can be found, including both liquid and gaseous carbon dioxide and a diaspore needle. Because diaspore’s refractive index (nα = 1.682–1.706; nβ = 1.705–1.725; nγ = 1.730–1.752) is so close to corundum (nω = 1.762; nε = 1.770) the diaspore needle almost disappears into the sapphire, appearing like a narrow indentation into the negative crystal. Liquid carbon dioxide becomes a gas at a fairly low temperature, with just the heat of the microscope causing the bubble to disappear. Intact negative crystals such as this are positive proof that the specimen has not been heat treated. Right: Reflected light reveals surface detail that is masked in transmitted light. Photos: Richard W. Hughes

Left: In this flattened negative crystal in a Sri Lankan padparadscha sapphire, multiple phases can be found, including both liquid and gaseous carbon dioxide and a diaspore needle. Because diaspore’s refractive index (nα = 1.682–1.706; nβ = 1.705–1.725; nγ = 1.730–1.752) is so close to corundum (nω = 1.762; nε = 1.770) the diaspore needle almost disappears into the sapphire, appearing like a narrow indentation into the negative crystal. Liquid carbon dioxide becomes a gas at a fairly low temperature, with just the heat of the microscope causing the bubble to disappear. Intact negative crystals such as this are positive proof that the specimen has not been heat treated.
Right: Reflected light reveals surface detail that is masked in transmitted light. Photos: Richard W. Hughes
Left: A fingerprint with many small negative crystal channels showing no signs of heat-induced damage in a sapphire from Madagascar. Right: In this heat-altered fingerprint, one can clearly see that each of the negative crystal channels has burst from the heat treatment. Also note the glassy circular "discoid" fissures. Photos: E. Billie Hughes

Left: A fingerprint with many small negative crystal channels showing no signs of heat-induced damage in a sapphire from Madagascar.
Right: In this heat-altered fingerprint, one can clearly see that each of the negative crystal channels has burst from the heat treatment. Also note the glassy circular "discoid" fissures. Photos: E. Billie Hughes
Brown monazite crystals are sometimes found in sapphires from Madagascar’s Ilakaka region. In this gem one can see glassy tension halos around each, indicating that the gem was subjected to low temperature (less than 1400°C) heat treatment. When viewed with dark-field illumination, the glassy tension halos around each monazite crystal are more distinct.

Left: Brown monazite crystals are sometimes found in sapphires from Madagascar’s Ilakaka region. In this gem one can see glassy tension halos around each, indicating that the gem was subjected to low temperature (less than 1400°C) heat treatment.
Right: When viewed with dark-field illumination, the glassy tension halos around each monazite crystal are more distinct. Photos: E. Billie Hughes
Left: A heat-altered crystal with an iridescent decrepitation halo, alongside a surface cavity filled with glass. Right: When the direction of the reflected light is changed to show the surface, it reveals patches of glass on the surface (right). Photos: Richard W. Hughes

Left: A heat-altered crystal with an iridescent decrepitation halo, alongside a surface cavity filled with glass.
Right: When the direction of the reflected light is changed to show the surface, it reveals patches of glass on the surface (right). Photos: Richard W. Hughes
When a crystal is heated (either by a magma or artificially by human intervention), it expands. Tension is often relieved by a fissure in the weakest direction, which in corundum is in the basal plane. Such fissures are difficult to see in dark-field illumination. If the lighting is changed from dark field to overhead fiber-optic, the flat tension disc appears in dramatic relief. This example is in a heat-treated blue sapphire from Bo Ploi (Kanchanaburi), Thailand. Such inclusions are quite common in both rubies and sapphires recovered from magmatic sources.

Left: When a crystal is heated (either by a magma or artificially by human intervention), it expands. Tension is often relieved by a fissure in the weakest direction, which in corundum is in the basal plane. Such fissures are difficult to see in dark-field illumination.
Right: If the lighting is changed from dark field to overhead fiber-optic, the flat tension disc appears in dramatic relief. This example is in a heat-treated blue sapphire from Bo Ploi (Kanchanaburi), Thailand. Such inclusions are quite common in both rubies and sapphires recovered from magmatic sources. Photos: Richard W. Hughes
Left: Kashmir sapphires are unique in that the skin of many crystals feature deep blue spots of color, like spots on a leopard’s back. Right: These blue spots are sometimes incorporated into finished stones, where they will be found just below the surface. Photos: Richard W. Hughes

Left: Kashmir sapphires are unique in that the skin of many crystals feature deep blue spots of color, like spots on a leopard’s back.
Right: These blue spots are sometimes incorporated into finished stones, where they will be found just below the surface. Photos: Richard W. Hughes
Left: Secondary "fingerprint" in a Mong Hsu (Myanmar) ruby before heating. Note the angular nature of the negative crystal channels. Right: Following heat treatment with flux, one can see the "necking down" and rounding of the channels. For more on this, see "Fluxed Up: The Fracture Healing of Ruby." Photos: Richard W. Hughes

Left: Secondary "fingerprint" in a Mong Hsu (Myanmar) ruby before heating. Note the angular nature of the negative crystal channels.
Right: Following heat treatment with flux, one can see the "necking down" and rounding of the channels. For more on this, see "Fluxed Up: The Fracture Healing of Ruby." Photos: Richard W. Hughes
Left: A lovely rosette inclusion surrounds a mica crystal in this ruby from Mozambique’s Montepuez region. This “rosette” actually consists of negative crystals flattened in the plane of basal pinacoid (perpendicular to the c axis). Oblique fiber-optic lighting. Right: When viewed with dark field and oblique fiber-optic illumination, the appearance changes dramatically, illustrating the importance of utilizing various illumination techniques with the microscope. Photos: Richard W. Hughes

Left: A lovely rosette inclusion surrounds a mica crystal in this ruby from Mozambique’s Montepuez region. This “rosette” actually consists of negative crystals flattened in the plane of basal pinacoid (perpendicular to the c axis). Oblique fiber-optic lighting.
Right: When viewed with dark field and oblique fiber-optic illumination, the appearance changes dramatically, illustrating the importance of utilizing various illumination techniques with the microscope. Photos: Richard W. Hughes
Left: Mozambique silk before heating shows a high luster rutile needle and an attached lower luster daughter crystal. Right: When such a stone is heated to a high enough temperature, the daughter crystal begins to break down. Photos: E. Billie Hughes & Richard W. Hughes

Left: Mozambique silk before heating shows a high luster rutile needle and an attached lower luster daughter crystal.
Right: When such a stone is heated to a high enough temperature, the daughter crystal begins to break down. Photos: E. Billie Hughes & Richard W. Hughes
Left: Undissolved rutile silk in sapphire. This forms along three directions, intersecting at 60/120° in the plane of the basal pinacoid (perpendicular to the c axis). Right: When a rutile silk-bearing sapphire is heated at a high temperatures (1400°C or more), the titanium quickly moves into solid solution, while other impurities (such as iron) do not, leaving behind silk skeletons. Photos: Richard W. Hughes

Left: Undissolved rutile silk in sapphire. This forms along three directions, intersecting at 60/120° in the plane of the basal pinacoid (perpendicular to the c axis).
Right: When a rutile silk-bearing sapphire is heated at a high temperatures (1400°C or more), the titanium quickly moves into solid solution, while other impurities (such as iron) do not, leaving behind silk skeletons. Photos: Richard W. Hughes
Left: Negative crystals in an untreated Mogok, Myanmar (Burma) sapphire in transmitted light.  Right: When illuminated with a fiber optic light from above, small exsolved plates become visible, in addition to the negative crystals. Photos: E. Billie Hughes

Left: Negative crystals in an untreated Mogok, Myanmar (Burma) sapphire in transmitted light. 
Right: When illuminated with a fiber optic light from above, small exsolved plates become visible, in addition to the negative crystals. Photos: E. Billie Hughes
Left: Transparent crystals, seen at left in transmitted light, can be hard to distinguish from negative crystals.  Right: However when observed between crossed polars (right), the interference colors reveal their doubly refractive nature. Untreated sapphire from Sri Lanka. Photos: E. Billie Hughes

Left: Transparent crystals, seen at left in transmitted light, can be hard to distinguish from negative crystals. 
Right: However when observed between crossed polars (right), the interference colors reveal their doubly refractive nature. Untreated sapphire from Sri Lanka. Photos: E. Billie Hughes
Left: With oblique fiber optic illumination, primary rutile crystals in an untreated Madagascar ruby show a dark red color. Right: In reflected light, we can also see that they display a submetallic luster where they were cut through on the surface. Photos: Richard W. Hughes

Left: With oblique fiber optic illumination, primary rutile crystals in an untreated Madagascar ruby show a dark red color.
Right: In reflected light, we can also see that they display a submetallic luster where they were cut through on the surface. Photos: Richard W. Hughes
Left: This ruby from Madagascar contains a large cavity with a mobile CO2 bubble. Right: As the gem is rotated in the stoneholder, the bubble moves. Such fluid-filled cavities (generally filled with liquid and gaseous CO2) cannot withstand heat treatment and thus are proof of natural origin. Photos: E. Billie Hughes

Left: This ruby from Madagascar contains a large cavity with a mobile CO2 bubble.
Right: As the gem is rotated in the stoneholder, the bubble moves. Such fluid-filled cavities (generally filled with liquid and gaseous CO2) cannot withstand heat treatment and thus are proof of natural origin. Photos: E. Billie Hughes
Left: Birefringent crystals light up in different colors in this sapphire from Sri Lanka when viewed between crossed polars. Right: Note the change in appearance of the included crystals when viewed between parallel polars. Photos: E. Billie Hughes

Left: Birefringent crystals light up in different colors in this sapphire from Sri Lanka when viewed between crossed polars.
Right: Note the change in appearance of the included crystals when viewed between parallel polars. Photos: E. Billie Hughes
Left: Partially healed "fingerprint" in a Sri Lankan sapphire, before heating. Note the pristine nature of the tiny negative crystals. Right: Heating of such a fingerprint causes tiny microfractures as the negative crystals burst, creating shiny discoid areas and a hazy appearance. Photos: E. Billie Hughes

Left: Partially healed "fingerprint" in a Sri Lankan sapphire, before heating. Note the pristine nature of the tiny negative crystals.
Right: Heating of such a fingerprint causes tiny microfractures as the negative crystals burst, creating shiny discoid areas and a hazy appearance. Photos: E. Billie Hughes
Left: Laser-Induced-Breakdown-Spectroscopy (LIBS) is used by some gem labs to test for beryllium. Unlike Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA-ICPMS), the surface is actually melted (rather than ablated), producing the circular rippled mark we see in the center of the girdle on the stone at left. Right: In contrast, LA-ICPMS ablates the gem, producing the symmetrical holes we see in the image at right. Photos: Richard W. Hughes & E. Billie Hughes

Left: Laser-Induced-Breakdown-Spectroscopy (LIBS) is used by some gem labs to test for beryllium. Unlike Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA-ICPMS), the surface is actually melted (rather than ablated), producing the circular rippled mark we see in the center of the girdle on the stone at left.
Right: In contrast, LA-ICPMS ablates the gem, producing the symmetrical holes we see in the image at right. Photos: Richard W. Hughes & E. Billie Hughes

 

 
 
 
 
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