October Birthstones | How to buy the Opal Gemstone

OCTOBER BIRTHSTONES

Opal

How to Buy Opal



Opal has been a good luck charm for centuries—though recent superstitions consider it a lucky gemstone only for people born in October, and unlucky to anyone else.

However, opal’s kaleidoscopic play-of-color can suit many changing moods and tastes to make this gemstone appropriate for anyone. It is also the traditional gift to celebrate 14th wedding anniversaries.

Like diamonds, opals can be evaluated by color, clarity, cut and carat weight. But these unique gemstones also have several additional conditions to consider.

Opal gems and jewelry should be stored in a place where they aren’t exposed to high temperatures or low humidity in order to avoid dehydration and crazing. Be sure they are in a padded cloth bag to avoid being scratched by other jewelry. For longer storage periods, place your opal in cotton wool with a few drops of water.

Color
Color is the key factor of opal quality: both the background “body color” and the flashing “play-of-color.” Dark backgrounds provide more contrast against vivid play-of-color, making black opal more highly valued than milky white varieties.

Warm colors like red and orange are generally rarer and more valuable than common blues and greens, although color range and coverage also play a role.

Pattern
Pattern is another factor unique to opal. Descriptive names like “stained glass,” “peacock,” “rolling fire,” and “Chinese writing” distinguish opal patterns. Gemologists typically prefer large, concentrated patches over small specks.

Clarity
Different opal varieties have varying clarity standards. Crystal opals should be transparent, while opacity makes black opals more valuable. A cloudy, milky haze lowers any opal’s value, and may indicate instability.

Due to high water content, opal can easily crack or “craze” under extreme temperatures, dehydration, or direct light. Crazed opal sells at much lower prices, and is more susceptible to fracture. Even high-quality opal demands delicate care to preserve its unique beauty.

Cut
Fine opals are often cut into irregular shapes to emphasize play-of-color. When possible, opals should be cut cabochon with rounded domes. But most opal comes in thin layers, which are commonly mounted on another dark stone like onyx or obsidian (as a doublet) and sometimes capped with clear glass or plastic (as a triplet) to make this fragile gemstone more wearable.

Opal gemstones may be treated with wax, oil, smoke, plastic or other additives to enhance luster. Identifying enhancements or synthetic materials may require specialized lab equipment, so it’s best to work with an American Gem Society jeweler who understands the criteria that determine opal’s value.

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The American Gem Society (AGS) is a nonprofit trade association of fine jewelry professionals dedicated to setting, maintaining and promoting the highest standards of ethical conduct and professional behavior through education, accreditation, recertification of its membership, gemological standards, and gemological research.

The Society is committed to providing educational products to inform and protect the consumer and to contributing to the betterment of the trade by creating industry standards to protect the jewelry-buying public and the fine jewelry industry as a whole.

AGS Laboratories, founded to support the AGS mission, is a nonprofit diamond grading laboratory with a mission of consumer protection. Adhering to the AGS Diamond Grading Standards, AGS Laboratories is dedicated to offering diamond grading reports that provide consistency and accuracy based on science.

American Gem Society

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info@ags.org (866) 805-6500