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Gem Knowledge

 

Whether in faceted stones, crystal specimens, polished pebbles or beads, amethyst has enjoyed popularity in nearly every culture throughout its ancient history. Before the lucrative deposits of Africa and South America were discovered, amethyst was as treasured as ruby and emerald. February's traditional birthstone, striking purple amethyst is the most popular gemstone of the quartz group.
 
ALTERNATE NAMES Spirit Quartz If It Has Secondary Pale Amethyst Growth Coverage, Rose Of France If Pale Lilac
 
COLORS Purple Through Violetish Purple
 
AMETHYST CLASSIFICATION
  • Common Name
    Amethyst
  • Species
    Quartz
  • Variety
    Amethyst
  • Colors
    Purple Through Violetish Purple
  • Alternate Names
    Spirit Quartz If It Has Secondary Pale Amethyst Growth Coverage, Rose Of France If Pale Lilac
  • Gemstone Groups
     
  • Key Separations
    Refractive index, birefringence, optic character and optic figure. A bull's-eye optic figure is determinative for quartz. Might also show Airy's spiral. The presence of Brazil-law twinning is a means of separating amethyst from scapolite.
  • Comments
    Amethyst is commonly found in geodes. Stones might be piezoelectric: able to generate electricity produced by mechanical pressure, Pyroelectricity: development of opposite charges at the ends of the axis due to change in temperature and triboluminescent: luminescence produced by friction.
AMETHYST OPTICAL PROPERTIES
  • Transparency
    Transparent - Translucent
  • Refractive Index
    1.544-1.553
    Tolerance:very constant
  • Birefringence
    0.009-0.009
  • Optic Character
    Uniaxial
  • Optic Sign
    Positive
  • Polariscope Reaction
    Doubly Refractive (DR)
  • Fluorescence
    SWUV: Inert to weak blue
    LWUV: Inert
  • CCF Reaction
     
  • Pleochroism
    Dichroic, weak to moderate purple and reddish purple
  • Dispersion
    Strength: weak fire Value: 0.013
  • Comments
     

 

AMETHYST CHEMISTRY & CRYSTALLOGRAPHY
  • Chemical Name
    silicon dioxide (aka silica)
  • Chemical Formula
    SiO2
  • Synthesis
     
  • Crystal System
    Trigonal
  • Classification
    Silicate
  • Nature
    Natural
  • Crystallinity
    Crystalline
  • Comments
     
AMETHYST CHARACTERISTIC PHYSICAL PROPERTIES
  • Hardness
    7
  • Streak
    White
  • Specific Gravity
    2.64-2.69 Range:0.03/-0.02 Typical:2.66
  • Toughness
    Good
  • Inclusions
    Amethyst is a type II clarity stone. Color zoning in stones is often present in the form of "soap scum", "tiger stripes" or "zebra stripes", crystals, negative crystals, liquid inclusions, two-phase inclusions, partially-healed fractures, hematite needles.
  • Luster
    Vitreous
  • Stability
    Good
  • Fracture
    Conchoidal
  • Cleavage
    None
  • Comments
     
 
HISTORY Amethyst's existence has been known since ancient times. Ancient Greeks, Romans, and Egyptians used amethysts in jewelry and household goods like bowls and cups. Even in ancient Mesopotamia, amethysts were engraved with royal and religious insignia and used as tools to imprint clay tablets. Amethyst has been symbolic of purity and royalty used in jewelry for hundreds of years. Amethyst has long played an important role in religion, as the stone in Christian bishops' rings and in rosaries.
 
ORIGIN Amethyst gets its name from the Greek words amethystos or amethustos, meaning "not drunken," because of the ancient belief that drinking wine from an amethyst cup--or, unfortunately, grinding amethyst into powder and adding it to wine--would help maintain sobriety.
 
LEARN MORE Amethyst was considered a symbol of a bishop's fine spirituality in the early Christian church. Amethyst rings soon became a standard part of a bishop's regalia, and for this reason, high-quality, fine-color amethyst is sometimes referred to as "bishop's grade" in the gemstone industry.