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Behind The Birthstone: Opal for October

Opal, derived from the Sanskrit word “upala” or valuable stone, symbolizes purity, innocence and hope. The basic structure of this stone, unlike other gems which are crystalline, is a hardened silica gel. A gem with cosmic qualities, in 2008, NASA announced that Mars also contains opal deposits.

Both Libras and Scorpios can find a wide selection of opal jewelry to add to their birthday wishlist that will add just the right amount of color and fun. To help celebrate this birthstone, we’ve rounded up a few fun facts and some new arrivals to for gifting inspiration.

fire opals
  • Opals can contain up to 20% water trapped within its silica structure.
  • This gemstone is formed after seasonal rains drench dry ground in regions such as Australia, carrying dissolved silica downward. When conditions dry up, the water evaporates and the silica deposits left behind form opals.
  • Opal is known for its unique display of flashing rainbow colors called play-of-color. There are two broad classes of opal: precious and common. Precious displays play-of-color, common do not.
  • There are five main types of opal:
    • White opal – translucent to semi-translucent, with play-of-color against a white or light gray background color, called body color.
    • Black opal – translucent to opaque, with play-of-color against a black or dark background.
    • Fire opal – transparent to translucent, with brown, yellow, orange, or red body color. This material—which often doesn’t show play-of-color—is also known as “Mexican opal.”
    • Boulder opal – translucent to opaque, with play-of-color against a light to dark background. Fragments of the surrounding rock, called matrix, become part of the finished gem.
    • Crystal or water opal – transparent to semitransparent, with a clear background. This type shows exceptional play-of-color.
  • Clarity refers to the degree of transparency present and its freedom from inclusions. Experts prize different levels of clarity for different opal types.
boulder opal and diamond ring
  • Play-of-color occurs in precious opal because it’s made up of sub-microscopic spheres stacked in a grid-like pattern—like layers of Ping-Pong balls in a box.
  • When buying this gemstone, play-of-color is the most important quality factor.
  • As the light waves travel between the spheres, the waves diffract or bend. As they bend, they break up into the colors of the rainbow, called spectral colors.
  • Because it can contain the colors of other gems, the Romans thought this stone was the most precious and powerful of them all.
  • It also symbolized love and hope for the Romans.
diamond & opal necklaces
  • Many cultures have credited this stone with supernatural origins and powers.
  • Arabic legends say it falls from the heavens in flashes of lightning. The ancient Greeks believed opals gave their owners the gift of prophecy and guarded them against disease. Europeans have long considered the gem a symbol of hope, purity, and truth.
  • Most opals are cut as cabochons because domed surfaces give the best play-of-color.
  • In 2008, Australia officially recognized the popularity of black opal and proclaimed it the official state gemstone for New South Wales.
  • The Aztec Indians of Mexico were among some of the first people to discover the fire opal. They called it “Quetzalitzlipyollitli” which means “Stone of the Bird of Paradise”.

For more opal facts, treatment and care tips visit our gemstone guide here and browse below for necklaces, rings, earrings and bracelets sure to put a smile on any October babies’ face.





Facts sourced from American Gem Society and The Gemological Institute of America

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