What is Opal
Opal has the same main composition as Quartz which is silica yet Quartz is crystallization that crystal can be seen by naked eyes, and Opal, on the other hand, is amorphous which means no crystal exist, this explains the reason why the hardness of Opal is only 6, softer than Quartz. The water content of an Opal may ranges from 3% to 10% and some can reach as high as 20%, if water evaporate Opal may crack or even break. Opal is known for its special characteristic, play of color, lights diffract when they go through tiny spaces between silica balls inside Opal and show different colors on the surface. Not every Opal displays play of color, therefore, distinct from other kinds of gemstones that decide their price by size, the value of Opal depends on whether the stone shows play of color and how colorful it is. Opals that display play of color are called Precious Opal, and most Opals that are treated as gemstones are these ones.
Types of Opal
Black OpalAlso called Dark Opal. With its dark body color, play of color looks more obvious. This kind of Opal is the most expensive.
White OpalA common kind of Opal with white body color. Play of color does not display as obvious as ones of the Black Opal, but whenever a conspicuous one is found, the price will be a lot higher, thus, White Opal is the kind with large price difference.
Fire OpalThe body color of Fire Opal is tangerine or yellow, and not all of them show play of color. Unlike other kinds of Opal which decide their value firstly by play of color phenomenon, Fire Opal depends on their body color mostly.
Opal Doublet and Triplet
Opal Doublet and Triplet are two common ways of Opal treatment. Opal Doublet is gluing a dark and harder stone at the back of an Opal slice, with the stone behind, Opal become firmer and play of color display better with a dark background. Opal Triplet is adding a clear Quartz or glass on the top of a Opal Doublet for protection. Opal Doublets and Triplets are a lot cheaper because only a small part of them are real precious Opal, they are usually in bezel sets when selling as jewelry because the set can cover the join of Opal and gives people the image of bigger natural Opal than it actually is.
History and Legend of Opal
- Opal was once considered to be the stone of disaster, the beginning of this rumor was a book written in 1829 by an English writer, Sir Walter Scott. In the book there is a woman who is accused to be a demoness, she has an Opal that changes colors along with her emotion. In the end, the Opal loses its color when a drop of holy water fells on it, the woman soon becomes ill and turns into ashes with the Opal. People at that time believed that Sir Walter Scott was implicating that Opal was ominous, then all of a sudden the value of Opal declined drastically and did not increase until Black Opal was discovered in Australia 50 years later.
- Another reason that Opal was viewed to be ominous is that when the technology was not well developed, Opal often crack because of water evaporation while people were making jewelry. Jewelry makers could not understood why so they started to think that Opal is sinister.
- Ancient Greeks regarded Opal as the tears that Zeus fall when he won the war against Titans.
- People in Middle Ages trusted that Opal could prevent their hair color from being dark or faded. Women with blond hair at that time would eagerly want an Opal necklace as a gift.
Origin of Opal
Australia is the principal origin of Opal, they produce about 90% of global production and Opal become national gemstone of Australia. Mexico is also known by its high quality Fire Opal. Other countries like Brazil, America and South Africa has small production, too.