However, there is a downside and as the most delicate gemstones we wear as jewelry, opals do require special care to ensure their beauty and longevity.
The most interesting and beautiful characteristic of precious opal is its internal color play often referred to as its “flash” or “light show”. This
phenomena and the rich and varied folklore associated with the opal makes it one of the most intriquing of the gemstones. Opals even have their own descriptive vocabulary such as:Play of color which is the phenomena of flashing or moving colors due to diffraction and not related to the body color.
Noble opal or Precious opal - Opal that exhibits play of color.
Common opal or Potch is translucent to opaque opal without play of color.
Fire in opal refers to play of color. (Fire opal is named for its body color and may or may not have play of color.)
Crazing refers to the cracks that develop as an opal dehydrates.
The value of precious opal is based on its size, background color and quality of its other colors, and the intensity of the color display. Soft whites or light blue shades are the most common colors for precious opal. Blue and green
are also very common in most precious opal. However, those opals which contain reds, oranges, and violets are considered more desirable. Black opal is predominantly dark-gray to blue-black and is the rarest and most highly desired of all the precious opals. Black opals exhibiting reds and oranges are the most valuable of all and often in the same price range as diamond, emerald, and ruby.Gemologically speaking, opal is hydrated silica and has no crystal structure (isomorphic). It is a low temperature mineral found in cracks and cavities that are filled in late in their geological life. Water must be present during their formation. It is also found as a replacement after certain skeletons of marine animals or plants. Opal is found in California, Nevada, and Idaho in the USA, Mexico, Brazil, Australia, and Hungary.
Care of Your Opal Jewelry
Opals have a hardness of 5.5 to 6.5 on the MOHS Hardness Scale (where a diamond is 10) and require special care to ensure their beauty and longevity.
Opals are delicate, but most certainly well worth the extra care. The opal’s water content is the most important weakness and if allowed to dry, the opal will crack and craze. In dry climates some precautions are necessary. Keeping them in a tight plastic bag, with a damp piece of cotton or fabric will help prevent dehydration.Because of their water content, opals are also highly sensitive to sudden changes in temperature. While opals can withstand either hot or cold temperatures, sudden temperature changes as in going into a cold winter’s day from a warm heated house may crack the opal. In this case it would be wise to wear your opal under clothing to protect them from that rate of temperature change. Opals also should not be stored near heat or cold sources which could expose them to sudden temperature changes.
Opals are fairly soft and therefore scratch easily. Simply wiping the dust off an opal will gradually reduce its polish. Clean opals using a soft cloth or brush, a mild detergent, and room temperature water, then rinse to remove any residue. Clean doublets and triplets with the same method, and never soak them as soaking can loosen the glue which attaches the layers.
Wear your opals as earrings, pendants, and brooches as these pieces are less likely to come into contact with harder objects that have the potential to scratch them. Opal rings should be in protective settings and considered as occasional wear only and special occasions. An opal ring worn regularly will have to be repolished often. Opals are porous and will absorb liquids so if you wear opal rings always remove them when doing dishes or using cleaning solutions. Common sense dictates that opal rings should not be worn while gardening or during sports activities.
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