Podcast
Questions and Answers
What is the primary factor that differentiates quartz varieties?
What is the primary factor that differentiates quartz varieties?
- Crystal size (correct)
- Clarity
- Hardness
- Color
What is the typical treatment process for producing citrine?
What is the typical treatment process for producing citrine?
- Dyeing
- Heat treatment of amethyst (correct)
- Irradiation
- Bleaching
Why is smoky quartz ideal for gem carvers and sculptors?
Why is smoky quartz ideal for gem carvers and sculptors?
- Its bright color
- Its rarity
- Its high price
- Its large crystal size and lack of flaws (correct)
What is the characteristic of the finest amethyst color?
What is the characteristic of the finest amethyst color?
What is the main factor in grading amethyst?
What is the main factor in grading amethyst?
What is the common trade name for treated black chalcedony?
What is the common trade name for treated black chalcedony?
Which country is the largest source of commercial-quality amethyst?
Which country is the largest source of commercial-quality amethyst?
What is a common practice among collectors of agates?
What is a common practice among collectors of agates?
What is the characteristic of the finest chrysoprase color?
What is the characteristic of the finest chrysoprase color?
What type of quartz exhibits a bumpy appearance similar to a bunch of grapes?
What type of quartz exhibits a bumpy appearance similar to a bunch of grapes?
What is the term for a type of quartz with curved or angular bands or layers that differ in color and transparency?
What is the term for a type of quartz with curved or angular bands or layers that differ in color and transparency?
What is the property of some crystals that generates an electrical charge when subjected to mechanical stress?
What is the property of some crystals that generates an electrical charge when subjected to mechanical stress?
What type of gem has a flat or slightly domed top and is often set in men's rings and cufflinks?
What type of gem has a flat or slightly domed top and is often set in men's rings and cufflinks?
What is the term for a type of quartz that is transparent and contains eye-visible inclusions?
What is the term for a type of quartz that is transparent and contains eye-visible inclusions?
What is the term for a type of Sagenitic quartz that contains needle-like rutile inclusions?
What is the term for a type of Sagenitic quartz that contains needle-like rutile inclusions?
What is the term for a type of quartz that contains needle-like or rod-like tourmaline inclusions?
What is the term for a type of quartz that contains needle-like or rod-like tourmaline inclusions?
What is the term for a type of cryptocrystalline quartz aggregate?
What is the term for a type of cryptocrystalline quartz aggregate?
What type of quartz is often characterized by its curved or angular bands or layers of different colors and transparency?
What type of quartz is often characterized by its curved or angular bands or layers of different colors and transparency?
What type of quartz contains eye-visible inclusions and is often transparent?
What type of quartz contains eye-visible inclusions and is often transparent?
Which Amethyst often a deep color even in small sizes?
Which Amethyst often a deep color even in small sizes?
Being the one of the first gems to be fashioned, how many years has chalcedony used in jewelry?
Being the one of the first gems to be fashioned, how many years has chalcedony used in jewelry?
Which Chalcedony varieties is considered to be the most valuable ?
Which Chalcedony varieties is considered to be the most valuable ?
Treated black Chalcedony's trade name is ...?
Treated black Chalcedony's trade name is ...?
Which Chalcedony variety is sold in larger quantities than any other ?
Which Chalcedony variety is sold in larger quantities than any other ?
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Study Notes
Quartz Varieties
- Quartz varieties differ mostly in the size of their crystals.
- Many gem-quality quartz varieties are routinely heated, bleached, or dyed.
Citrine
- The finest citrine color is a saturated yellow to reddish orange, free of brownish tints.
- Most citrine on the market is produced by heat treatment of amethyst.
Chalcedony
- The gem trade considers chalcedony a separate species from large-crystal quartz varieties.
- Chalcedony has been used in jewelry for almost 3,000 years.
- Treated black chalcedony—known in the trade as black onyx—is sold in larger quantities than any other chalcedony variety.
Amethyst
- One of the most popular colored gemstones due to its wide availability, affordable price, and attractive color.
- Varied color distribution within amethyst rough yields fashioned gems in a wide variety of tones and saturations.
- The finest amethysts are a strongly saturated, medium-dark to dark reddish purple or purple, with no visible color zoning.
- Amethyst is sold in a variety of grades based mainly on color.
Chrysoprase
- The finest chrysoprase color is a light to medium yellowish green.
Smoky Quartz
- Smoky quartz crystals are often large, inexpensive, and free from flaws, making them ideal for gem carvers and sculptors.
Other Key Terms
- Agate: Chalcedony with curved or angular bands or layers that differ in color and transparency.
- Sagenitic quartz: Transparent quartz, usually rock crystal, that contains eye-visible inclusions.
- Botryoidal: A crystal growth habit with a bumpy appearance similar to a bunch of grapes.
- Signet: A tablet-cut gem with a flat or slightly domed top and sometimes a carved design, typically set in men's rings and cufflinks.
- Piezoelectricity: A property of some crystals that causes them to generate an electrical charge when subjected to mechanical stress.
- Tourmalinated quartz: A type of sagenitic quartz containing needle-like or rod-like tourmaline inclusions.
- Rutilated quartz: A type of sagenitic quartz containing needle-like rutile inclusions.
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