About opals we know that they are really beautiful and fascinating gemstones like no other. For, in them it is possible to see many colors shining unpredictably in a single stone. To which we must add the fact that, unlike most of the gemstones that exist, opals are amorphous. This means that they do not have a defined crystalline structure.

However, this incredible mix of colors and shapes are part of the magic that has allowed them to captivate many people for centuries and will continue to do so for many more. But besides admiring them, there is a lot to learn about them. So, surely you, like us, will enjoy discovering some facts that you probably did not know about these unique and colorful gemstones.

Interesting facts about opals
Image by Piqsels

Opal is the birthstone of October

If you were born in October, you may have already known this, but for those who didn’t, opal is the official birthstone of October. It’s not the only birthstone for October, though, as it shares this distinction with pink tourmaline, which is the other official birthstone for this month.

The rarest and most valuable opal is the black opal

This type of opal exhibits a beautiful and complete set of colors, ranging from yellow, blue and green to violet, deep red and orange. So, being one of the most beautiful gemstones, it is easy to deduce why it is also one of the most valuable. In fact, the more colorful it is, the more valuable it is. The color variations of black opal include various shades of gray to black. But there are also many different tones, shades, hues, tints and colors found within black opals. 

White opals are the most common type

White opals are the most common type and, while quite unique and beautiful, have the lowest market value of all opal types. They are also known as «Milky opals» and despite their lower value, they are very appreciated stones for energy work. So they are used to balance the chakras and eliminate negative emotions. Some have even called white opals the strongest of the healing stones, even labeling them as the stone of the Gods.

They are formed from rain

Something few people know about opals is that they are formed by seasonal rainfall. The process begins when water runs through the cracked earth, collecting bits of silica along the way and carrying this solution deep into the earth. When the water evaporates, it leaves a deposit of lumpy silica, which after repetitive cycles and over very long periods of time, ends up solidifying and forming an opal.

But to speak of very long periods of time is not an exaggeration, since most of the opals that are mined today were made between 65 and 145 million years ago. It takes approximately 5 million years to solidify just one centimeter of opal.

Believed to symbolize purity

According to history and tradition, opals are believed to be a symbol of purity and hope. In ancient times, it was believed that the use of opals brought luck and clarity of vision, but also happiness and beauty to the user.

Also meet a List of 23 gemstones and their meaning

They are not as fragile as we think

About opals there have been many misconceptions, specifically about their hardness. For many believe that because they are partly made of water and have a score of 5.5 to 6.5 on the Mohs hardness scale, they will not be as strong as other gemstones. But despite being outperformed by other more resistant stones such as amethysts, emeralds and rubies, this does not mean that they will crack or break at the slightest knock or fall.

However, as long as we avoid strenuous physical activities and manual labor while wearing our opal jewelry, or remove our jewelry, we can be assured that the opal will be safe.

It is possible that there may be found opals on Mars

Although in our planet there are few sources of this precious stone, another surprising fact is that they could also be found elsewhere in outer space. This is suggested by the findings of the rover that was sent to the planet Mars and which, in 2015 was able to detect in its exploration what appear to be opal deposits on the planet’s surface. So, the opal regions of Mars could now be a good target for future explorations in search of signs of life.

As we have already mentioned, opals are formed as a result of rain. This means that, in some way or another, water has existed or continues to exist on Mars. Maybe not on its surface, because its thin atmosphere prevents it, but it could remain liquid underground.

The origin of its name

It is believed that the name of the stone was adopted from the Latin word “opalus“. However, others believe it is derived from the old greek word “opallios“ meaning a change of color. Although about opals and its name it is possible that there is much in dispute and that it does not come from any of these words. Some say it is derived from the Sanskrit word “úpala“ which means precious stone.

They come mainly from Australia

The conditions necessary to form opals only occurred in certain parts of the world millions of years ago, which means that they appear in only a few places. These include: Brazil, Mexico, Hungary, the United States, Peru, Ethiopia and Nicaragua.

But a fact that some people probably don’t know about opals is that 95% of the world’s opals and specifically all black opals come from Australia. So it is no strange that it is the national gemstone of this country.  

They can be synthesized

What is possibly not known about opals, is that as with most gemstones, opals can also be manufactured in a laboratory. But this is not a recent development, the first opal created in a laboratory was first synthesized in 1974 by Pierre Gilson.

However, Since then, the technology for opal synthesis has greatly improved. As a result, lab-created opals today do not have the lizard-skin pattern they once had. This has allowed synthetic opals to have non-directional patterns that make them look much more like natural opals. Although lab created opals can still be distinguished due to the lack of inclusions in the stone.

They are classified as minerals, not as crystals

Opals are a hydrated amorphous form of silica and are considered mineraloids, as are obsidian, amber and pearl. A mineraloid is a naturally occurring substance that does not exhibit crystallinity, meaning that the atoms of the mineral are not arranged in crystalline structures, or the crystalline structure is not uniform.

Can contain up to 20% water

Because they do not have a hard crystalline structure, these mineraloids often retain a large amount of water. That can sometimes reach up to 20 percent of their weight, which can cause cracking. Although opals are cured in most cases to prevent cracking, extreme dryness can damage the stone. Therefore, it is not recommended to expose them to dry or hot environments. 

The oval cabochon is the most common cut for opals

When opals are cut to design jewelry, they are commonly made into oval cabochons. For this shape, not only because it brings out surface characteristics such as luster, but also provides the best color play and prevents the stone from breaking. But when it comes to exceptional opals, cutters sometimes consider giving them free shapes to maximize the play of colors.

The Virgin Rainbow is the most expensive opal in the world.

 The most expensive opal in the world is the Virgin Rainbow and is valued at more than 1.000.000 dollars. This exceptional specimen was discovered in Australia in 2003 by John Dunstan. It is an opal that was formed in the skeleton of a belemnite, an ancient ancestor of today’s cuttlefish. The good thing is that we can appreciate it in all its splendor. It is currently owned by the South Australian Museum, where it is on display.

ALFA