Opal’s brilliant display of kaleidoscopic colors mirrors the beautiful hues found throughout the season of autumn, making it the perfect birthstone for October! Read on to discover more about this stunning gemstone and what the LC has to offer when it comes to opal opulence.
With an internal mixture of fiery color, the opal is one of the most appealing and fascinating gems in the world. The best samples will exhibit a one-of-a-kind dazzling pattern of color and light, popular with jewelers all over the globe.
The development of this gemstone started millions of years ago when a mixture of silica and water flowed into cracks and holes in the ground. Over time, it hardened and solidified to turn into opal. Based on scientific estimates, it takes five million years to produce an opal just one centimeter thick.
Its unique display of flashing rainbow colors is known as play-of-color. Experts generally use five main groups to identify opals.

Crystal or Water Opal

Transparent to semitransparent, with a clear background. This group shows exceptional play-of-color.

White or Light Opal

Translucent to semi-translucent, with play-of-color against a white or light gray background.

Boulder Opal

Translucent to opaque, with multiple colors against a light to dark background. Fragments of the surrounding rock become part of the finished gem.

Fire Opal

Transparent to translucent, with brown, yellow, orange or red background. This stone often doesn’t have play-of-color like the other categories.

Black Opal

Translucent to opaque, with multiple colors against a black to other dark background.


An opal’s intensity, play-of-color and pattern are all important value factors. Fine opals are often cut into irregular shapes that keep as much play-of-color as possible. Because this gemstone has a relatively low density, even larger sizes can be comfortable to wear.

Now that you’ve had a chance to learn more about this October birthstone, here are three brilliant opals that the LC will offer this month!


Australian boulder opal is most celebrated for its spectacle of rainbow-like hues, which vary with

lighting and angle of observation. Not every opal has this rare color feature. It exhibits a dark body tone, which makes its vibrant colors stand out even more.

This solid opal can be found in cracks and cavities of ironstone. The stone occurs either as a strong color on top of the ironstone or as flecks of hues dispersed within the entire stone. With high density due to ironstone content, boulder opal is more resilient than other opals.


The Ethiopian Welo opal is stunning due to its lively play-of-color and fire. Often this vivid
display is featured throughout an entire piece. This particular opal is a hydrophane, meaning that it can soak up water like a sponge. When hydrated, the stone becomes more translucent, which makes the play of colors more defined. It reverts back to opaque once it releases water.


Jalisco fire opal is unique because it captures the glow of the volcanic lava streams within which it formed. Valued for its vibrant and passionate orange sparkle, this fiery gem is a favorite for collectors.

As its name suggests, this gem sprang from fire, specifically from the ancient volcanoes of the Jalisco region of Mexico. Nuggets of fire opal can be seen fixed in lava streams.

Jalisco fire opal formed when water seeped into molten rock, filling its crevices. With high temperature and tension, silica created a compact gel that trapped the water inside the stone. The ancient Maya, Aztec and Inca tribes called this treasure, the “stone of the bird of paradise.”

We know that we said we would only feature three opals, but we couldn’t help ourselves! The Sierra Madre purple opal is so new that you have to wait until we release it next month. Sorry for the tease, but we couldn’t resist. Stay on the look out for a glimpse of this rare and exotic gemstone coming, soon! 
For more information on all of our stunning gemstones, check out our Education Center!