OPAL: October Birthstone

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OPAL: October Birthstone

"The opal resembles a fraction of the rainbow softened by a milky cloud." - Charles Blanc

white gold opal and diamond cocktail ring
Opal is the traditional October birthstone and is also the stone given to celebrate the 14th wedding anniversary. It is believed to have originated in India, which is the source of the first opals brought to the Western world. In Sanskrit it was called upala, a “precious stone" and in ancient Rome, this became opalus. Most opals are valued for their shifting colors in rainbow hues – a phenomenon known as “play-of-color.”
At Devon's Diamonds & Decor, we have noticed that opal jewelry in Boca Raton has been a popular trend for quite some time now. Whether the gemstone is a connection to your birth month, a 14th wedding anniversary or you're into its "magical powers", a piece of opal jewelry makes the perfect gift.


The October birthstone’s dramatic play-of-color has inspired writers to compare it to fireworks, galaxies and volcanoes. The Bedouins once believed that opal held lightning and fell from the sky during thunderstorms. The Ancient Greeks thought that opals bestowed the gift of protection from disease. The Europeans long maintained opal to be a symbol of purity and truth. Hundreds of years ago, opal was believed to embody the virtues and powers of all colored stones. And because opal has the colors of other gems, the Romans thought it was the most precious and powerful of all.


The opal birthstone can be found in many places. The fields of Australia are the most productive in the world for the October birthstone. Ethiopia, Mexico and Brazil are also important sources. Additional deposits have been found in Central Europe, Honduras, Indonesia, Madagascar, Peru, Turkey and the United States.

How Opal is Formed

Opal is the product of seasonal rains that drenched dry ground in regions such as Australia’s semi-desert “outback.” The showers soaked deep into ancient underground rock, carrying dissolved silica (a compound of silicon and oxygen) downward. During dry periods, much of the water evaporated, leaving solid deposits of silica in the cracks and between the layers of underground sedimentary rock. The silica deposits formed opal. When opal formed, silica gel filled crevices in rock. As water evaporates, the silica is deposited in the form of tiny spheres. Opal contains up to 20% water trapped in its silica structure. Opal’s arrays of silica spheres form a fantastic variety of patterns and colors. No two opals are exactly alike, which is one of the reasons of why opal jewelry has been such a popular trend.


Although experts divide gem opals into many different categories, five of the main types are:
  • White or light opal: Translucent to semitranslucent, with play-of-color against a white or light gray background color, called bodycolor.
  • Black opal: Translucent to opaque, with play-of-color against a black or other dark background.
  • Fire opal: Transparent to translucent, with brown, yellow, orange, or red bodycolor. 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.


Opal Quality Factors

Play-of-color, intensity, and pattern are important value factors.
There are three main aspects of an opal’s quality:
  • Color—Background color and play-of-color
  • Pattern—Arrangement of play-of-color
  • Clarity—Transparency and quantity of inclusions
yellow gold opal and diamond cocktail ring
  • COLOR. Opal hues can range across the spectrum. An opal might display a single color, two or three colors, or all the colors of the rainbow. Opal displays background color in addition to play-of-color. Background color—also called bodycolor—is caused by the suspension of tiny impurities within opal’s silica spheres. Play-of-color might be the most spectacular aspect of an opal’s appearance. No matter the color or combination of colors, play-of-color must be vivid to command a high rating.
  • PATTERN. Pattern describes the arrangement of an opal’s play-of-color. Like the shapes you see in the clouds, play-of-color takes many forms.

Common terms for play-of-color patterns include:

    • Pinfire or pinpoint: Small, closely set patches of color
    • Harlequin or mosaic: Broad, angular, closely set patches of color
    • Flame: Sweeping reddish bands or streaks that shoot across the stone
    • Peacock: Mainly blue and green

In general, connoisseurs prefer large, closely arranged patches of color over tiny, scattered dots. As with any play-of-color, no matter what the pattern, colors must be bright for the stone to be valuable.

  • CLARITY & TRANSPARENCY. With an opal, clarity is its degree of transparency and freedom from inclusions. An opal’s clarity can range all the way from completely transparent to opaque. Experts prize different levels of clarity for different opal types.
  • CUT. The cutter considers an opal’s color, pattern, and clarity when planning the finished gem. As with many top-quality colored stones, exceptional opals might not be cut to standard sizes and shapes.
  • CARAT WEIGHT. Opals come in a wide range of sizes and carat weights. Opal has relatively low density compared to many other gemstones so even larger sizes can be comfortable to wear. Common sizes for many of the opal cabochons set in jewelry are 6×4, 7×5, and 8×6 mm.

yellow gold opal and diamond bangle bracelet

Opal Care and Cleaning

This October birthstone ranges from 5 to 6.5 on the Mohs Scale of Hardness. Opal is a fragile gemstone and because of its high water content, it can be affected by extreme temperature changes, and is easily damaged by impact. It is a gem suitable for jewelry but requires care when wearing to not scratch or break the stone. Opal is best worn as a pendant or as earrings, because it is less prone to damage. Make sure to store your opal jewelry by itself to prevent jewelry set with harder gems from scratching the opal. Diamonds, rubies, sapphires and emeralds are just a few of the gems that can scratch this birthstone. The safest way to clean an opal is with warm, soapy water.  Other cleaning methods might damage the opal or filler material so make sure that your opal jewelry is never put it in an ultrasonic cleaner.
opal and diamond dangling earrings

Opal Jewelry in Boca Raton

Devon's Diamonds & Decor offers a wonderful selection of gorgeous opal jewelry in Boca Raton. This October birthstone makes the perfect gift for your October-born friends and family, year-round. Stop by our jewelry store in Boca Raton and our family of fourth-generation jewelers will help you choose the perfect piece of opal jewelry. 
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