Chrysoberyl Vartries
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Questions and Answers

Which type of Chrysoberyl is characterized by a 'milk and honey' effect?

  • Chiastolite
  • Andalusite
  • Cat's Eye (correct)
  • Alexandrite

    • What are the primary sources of Alexandrite?

  • Sri Lanka and Brazil (correct)
  • Ural Mountains of Russia and Brazil
  • Myanmar's Mogok Stone Tract and East Africa
  • India

    • Which type of Chrysoberyl is known for its 'emerald by day, ruby by night' characteristic?

  • Alexandrite (correct)
  • Chiastolite
  • Andalusite
  • Cat's Eye

    • What is the typical carat weight range for Cat's Eye Chrysoberyl?

    <p>0.50 to 2.00 cts.</p> Signup and view all the answers

    Which type of Chrysoberyl is often used to create synthetic tanzanite?

    <p>Forsterite</p> Signup and view all the answers

    Where is the best quality Andalusite found?

    <p>Brazil</p> Signup and view all the answers

    What is the name of the synthetic process used to create green Chrysoberyl?

    <p>Pulling</p> Signup and view all the answers

    Which company was the first to produce a commercially available synthetic cat's-eye color-change alexandrite?

    <p>Kyocera Corporation</p> Signup and view all the answers

    What is the typical cut used for Cat's Eye Chrysoberyl?

    <p>Cabochon</p> Signup and view all the answers

    Which type of Chrysoberyl is known for its fine quality and even proportions?

    <p>Cat's Eye</p> Signup and view all the answers

    What is the name of the Chrysoberyl variety that exhibits a chatoyant band?

    <p>Cat's Eye</p> Signup and view all the answers

    What is the name of the Chrysoberyl variety that is formally known as 'chrysolite'?

    <p>Yellow Chrysoberyl</p> Signup and view all the answers

    Which of the following Chrysoberyl varieties is known for its strong color change or 'Alexandrite Effect'?

    <p>Alexandrite</p> Signup and view all the answers

    What is the name of the Chrysoberyl variety that is characterized by a semitransparent, golden yellow to slightly greenish yellow color?

    <p>Cat's Eye</p> Signup and view all the answers

    Which of the following Chrysoberyl varieties is colored by traces of vanadium?

    <p>Green Chrysoberyl</p> Signup and view all the answers

    What is the name of the Chrysoberyl variety that is characterized by a transparent, greenish yellow color with no chatoyancy?

    <p>Yellow Chrysoberyl</p> Signup and view all the answers

    Which of the following Chrysoberyl varieties is known for its pleochroic colors?

    <p>Cat's Eye</p> Signup and view all the answers

    What is the name of the Chrysoberyl variety that is characterized by a strong, bluish green to yellowish green color in daylight?

    <p>Alexandrite</p> Signup and view all the answers

    Which of the following Chrysoberyl varieties is formally known as 'Cymophane'?

    <p>Iolite</p> Signup and view all the answers

    What is the name of the Chrysoberyl variety that is characterized by a green, non-phenomenal color?

    <p>Green Chrysoberyl</p> Signup and view all the answers

    In which country is Iolite primarily found?

    <p>Sri Lanka</p> Signup and view all the answers

    What is the typical size range for Iolite?

    <p>1 to 10 cts.</p> Signup and view all the answers

    In which regions of Africa is Iolite found?

    <p>Central and Eastern Africa</p> Signup and view all the answers

    In which country is Iolite also found, apart from Sri Lanka?

    <p>Brazil</p> Signup and view all the answers

    What is the notable effect exhibited by Iolite?

    <p>Pleochroism</p> Signup and view all the answers

    Is Iolite known for its phenominal or non-phenominal properties?

    <p>Non-Phenominal</p> Signup and view all the answers

    What is the MOHS scale of Iolite?

    <p>7 to 7.5</p> Signup and view all the answers

    What is the chemical composition of Iolite?

    <p>Ilicate of aluminum, iron, and magnesium</p> Signup and view all the answers

    What is the typical source of Iolite?

    <p>Alluvial deposits</p> Signup and view all the answers

    What phenomenon is exhibited by Iolite?

    <p>Pleochroism</p> Signup and view all the answers

    What is the typical cut used for Iolite?

    <p>Cabochon</p> Signup and view all the answers

    What is the typical color range of Iolite?

    <p>Violetish blue to violet</p> Signup and view all the answers

    What is the hardness of Iolite compared to Tanzanite?

    <p>Harder than Tanzanite</p> Signup and view all the answers

    Is Iolite ever treated?

    <p>No, never treated</p> Signup and view all the answers

    What is the typical clarity of Iolite?

    <p>Transparent</p> Signup and view all the answers

    What is the typical color range of Andalusite?

    <p>Brownish or Yellowish green, finest being yellowish green to orange</p> Signup and view all the answers

    What is the chemical composition of Andalusite?

    <p>Aluminum silicate</p> Signup and view all the answers

    What is the notable phenomenon exhibited by Andalusite?

    <p>Pleochroism</p> Signup and view all the answers

    What is a unique characteristic of the Chiastolite type of Andalusite?

    <p>It has a distinct cross-shaped marking</p> Signup and view all the answers

    What is the typical clarity of Chiastolite?

    <p>Opaque</p> Signup and view all the answers

    What is the hardness of Andalusite on the MOHS scale?

    <p>7-7.5</p> Signup and view all the answers

    What is the typical cut used for Chiastolite ?

    <p>Cabochon or tablet</p> Signup and view all the answers

    Which of the following countries is known for producing Andalusite with the best hues?

    <p>Brazil</p> Signup and view all the answers

    What is the range of sizes for Andalusite?

    <p>1 to 10 cts.</p> Signup and view all the answers

    Which of the following is a characteristic of Andalusite?

    <p>Pleochroic colors</p> Signup and view all the answers

    In which of the following countries is Andalusite also found, apart from Brazil?

    <p>Sri Lanka</p> Signup and view all the answers

    What is the typical bodycolor of Andalusite?

    <p>Yellowish green</p> Signup and view all the answers

    Study Notes

    Gemstone Types and Characteristics

    • Alexandrite: rare, faceted mixed cut, exhibits color change, also known as "emerald by day, ruby by night"
    • Cat's Eye: cabochon with inclusions, fine quality has girdle-to-girdle inclusions, typically 0.50 to 2.00 cts.
    • Andalusite: faceted, sizes range from 1 to 10 cts., also known as Chiastolite
    • Tanzanite: variety of zoisite, typically faceted, fine quality is pure blue or intense violet-blue
    • Iolite: also known as Cordierite, transparent, violetish blue through violet hue, pleochroic colors range from light/dark violet to yellow/yellow-brown and blue gray

    Origins and Sources

    • Tanzanite: Merelani in northern Africa, near Tanzania
    • Iolite: Sri Lanka, several areas of Africa, Kenya, central Tanzania, and the island of Madagascar, India, Brazil, Norway, and Finland
    • Alexandrite: Ural Mountains of Russia, Sir Lanka, Brazil, India, Myanmar's Mogok Stone Tract, East Africa, and Madagascar
    • Cat's Eye: Sir Lanka, Brazil, Myanmar's Mogok Stone Tract, Zimbabwe, Madagascar, and Tanzania
    • Andalusite: Brazil, Sri Lanka, and Spain

    Synthetic Processes

    • Tanzanite: synthetic forsterite is used as synthetic tanzanite due to its pleochroic qualities
    • Alexandrite: produced using "Czochralski", floating zone, and flux methods
    • Green Chrysoberyl: vanadium is used to produce bluish green, nonphenomenal, pulled synthetic chrysoberyl

    Physical Properties

    • Tanzanite: Mohs scale 6 to 7
    • Iolite: Mohs scale 7 to 7.5
    • Alexandrite: Mohs scale 8.5
    • Andalusite: Mohs scale 7 to 7.5

    Phenomena and Characteristics

    • Tanzanite: exhibits pleochroism
    • Iolite: exhibits pleochroism
    • Alexandrite: exhibits color change or "the alexandrite effect" and cat's eye
    • Cat's Eye: exhibits chatoyancy and pleochroism
    • Andalusite: exhibits pleochroic colors, also hues of olive or brownish green, yellowish green, and brownish red

    Tanzanite

    • Named and promoted by Tiffany's in 1968
    • Found in Merelani, northern Africa, near Tanzania
    • Variety of zoisite
    • Fine quality is pure blue, intense violet-blue, or violet body color
    • Has a Mohs scale hardness of 6 to 7
    • Often heat-treated to enhance color

    Iolite

    • Also known as cordierite
    • Found in Sri Lanka, Africa, India, Brazil, Norway, and Finland
    • Transparent, violetish blue to violet hue
    • Has a Mohs scale hardness of 7 to 7.5
    • Often found in alluvial deposits

    Alexandrite

    • Variety of chrysoberyl
    • Found in Ural Mountains of Russia, Sri Lanka, Brazil, India, Myanmar, and East Africa
    • Has a strong color change effect, appearing bluish green in daylight and orangy red in incandescent light
    • Has a Mohs scale hardness of 8.5
    • Often found in alluvial deposits

    Cat's Eye Chrysoberyl

    • Type of chrysoberyl with a distinct, straight, silver-white chatoyant band
    • Found in Sri Lanka, Brazil, Myanmar, and Zimbabwe
    • Fine quality is semitransparent with a golden yellow to slightly greenish yellow or brownish yellow color
    • Often cut into a cabochon shape

    Andalusite

    • Found in Brazil, Sri Lanka, and Spain
    • Has a Mohs scale hardness of 7 to 7.5
    • Can appear in various colors, including brownish or yellowish green, orange, pink, or violet
    • Often found in alluvial deposits

    General Information

    • Pleochroism is a phenomenon where a gemstone appears to change color when viewed from different angles
    • The "Alexandrite Effect" is a specific type of color change phenomenon
    • Chatoyancy is a phenomenon where a gemstone appears to have a moving band of light
    • Many gemstones are treated or synthetic to enhance their appearance or color

    Tanzanite

    • Named and promoted by Tiffany's in 1968
    • Government control of the mine affects prices
    • TV promoted it to US consumers
    • Variety of zoisite
    • Mohs scale: 6 to 7
    • Fine quality is pure blue, intense violet-blue, or strong purplish pleochroic
    • Can be heat-treated to turn brown stone to blue and violet

    Iolite

    • Also known as "Cordierite"
    • Transparent, violetish blue to violet hue
    • Pleochroic colors range from light to dark violet and yellow to yellow-brown
    • Mohs scale: 7 to 7.5
    • Found in alluvial deposits
    • Cleavage in one direction makes it vulnerable when mounted

    Alexandrite

    • Variety of chrysoberyl
    • Mohs scale: 8.5
    • Very strongly bluish green to yellowish green in daylight, and orangy red to purplish red in incandescent light
    • Exhibits the "Alexandrite Effect"
    • Found in alluvial deposits
    • Mainly faceted, always cut to show best color change

    Cat's Eye Chrysoberyl

    • Chrysoberyl with a distinct, straight, silver-white chatoyant band
    • Fine quality is semitransparent, golden yellow to slightly greenish yellow, or brownish yellow
    • Can be pleochroic
    • Typically 0.50 to 2.00 cts.

    Andalusite

    • Aluminum silicate
    • Mohs scale: 7 to 7.5
    • Can be brownish or yellowish green to orangy brown, pure green, brown, pink, or violet
    • Finest quality is yellowish green and orange
    • Can be pleochroic, with colors tending towards reds, greens, and oranges
    • Found in Spain, Brazil, and Sri Lanka

    General Information

    • Largest consumers of these gemstones are not specified
    • Chemical composition: Tanzanite (silica, calcium, aluminum), Iolite (silicate of aluminum, iron, and magnesium), Alexandrite (beryllium aluminum oxide), Andalusite (aluminum silicate)
    • Forming sources: Iolite (alluvial deposits), Alexandrite (alluvial deposits), Andalusite (trace elements of iron and titanium)
    • Possible phenomena: Tanzanite (pleochroism), Iolite (pleochroism), Alexandrite (color change), Cat's Eye (chatoyancy), Andalusite (pleochroism)

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