Along with Tourmaline, Opal is the birthstone of October and the zodiac stone of Libra. Traditionally, these stones are given as a gift on the 14th wedding anniversary. These beautiful stones are the national gemstone of Australia.
Throughout the world, Opal is mostly known for its magnificent beauty and color. These stones symbolize love, peace, passion, loyalty, and positivity.
Let us learn more about the October birthstone, Opal.
Opal is typically a semi-transparent gemstone and a hydrated amorphous form of silica. It is an eye-catching stone with a spectrum of colors. Australia is one of the largest producers of Opal that produces almost 95% of these stones. Around 6-10% of water is present in most of these stones that are produced in Australia. Throughout history, these stones are widely valued by the people.
The people born in October are mostly calm, confident, passionate, and loyal. They know how to encourage the people around you and the surroundings are always cheerful when they are around. These beautiful traits make Tourmaline fitting to be the birthstone of October.
Opal was derived from the Greek word "opallios" which means "precious stone". The deposits of these stones were first discovered by Louis Leakey in a cave in Kenya. Most of the geologists believe that these stones originated from Ethiopia around 4000 BC.
For a long period, people from all over the world believed that Opal was an evil stone and it will bring bad luck. The market of these stones went down but when Black Opal was discovered in Australia, the market of these stones finally recovered.
The formation of Opal takes a large amount of time. Heavy rainfall causes the silica from sandstone to fall into rock crevices. After the water finishes evaporating, only silica gel remains. It will take a million years for the silica gel to harden and after it hardens, Opal is formed.
The chemical formula of Opal is Hydrated Silica (SiO₂·nH₂O). These stones have a hardness of 5.5-6 according to the Mohs scale and it has sub-vitreous to waxy luster.
The value of an Opal depends on many factors like - cut, size, brilliance, play of color, body tone, and faults. The price of these stones can range from $600-$1000. Black Opal is the most prized Opal and its value can be over $10000.
In 1956, the world's largest opal "Olympic Australis" was found in Coober Pedy, South Australia that weighs 17,000 carats. The world's most valuable Black Opal "The Aurora Australis" was found at Lightning Ridge in 1938. The estimated value of this stone is $1,000,000.