Boulder Opal – a colorful gemstone
Boulder opals were formerly also known as boulder matrix opals. These are opals that shimmer in a wide variety of colors. Other opal varieties include the fire opal, the black opal and the white opal.
Legends surrounding the boulder opal
The term opal probably comes from Greek or Latin. Depending on the source, the term “oculus” for eye or the term “opallios” for “seeing a color change” is used. There is also the thesis that the name comes from Sanskrit and means “precious stone jewel”.
“Boulder”, on the other hand, can be clearly assigned to the English word for ‘boulder’. Boulder opal was discovered relatively late (in 1875).
Other opals have been known for much longer. The indigenous people of Australia believed that the creator had placed the opals on the earth. For this, he had chosen exactly the place where he first touched the ground.
The ancient Arabs, on the other hand, were convinced that the opals came to earth in lightning bolts.
In the Middle Ages, the stones were associated with luck. It was said that they combined all the positive properties of the precious stones whose colors occur in them. The more colorful an opal was, the more positive properties it had.
In 1850, large opal deposits were discovered in Australia. Since then, many different opals have been mined there, including the boulder opal.
The opalescent boulder opal
Boulder opals not only have a color, but small channels of bright colors: white, blue, pink, yellow, green and red can occur in the same stone. These channels run through the yellow-brown mother rock. They take on different forms, from fine cracks to larger formations. This creates a great variety, no two stones are alike.
The shimmering play of colors in opals has been given its own name in technical jargon: opalescence. The Boulder Opal belongs to the opalescent opal family and is therefore more valuable than non-opal opals. It is also one of the few gemstones whose colors are never changed afterwards.
Instead, there is another method to emphasize the color variety of boulder opals: a dark, usually black rock is glued under a thin layer of opal. Two stones glued together in this way are called “doublets”. If the doublets are set in jewelry, the black layer is usually no longer visible.
Use: jewelry with boulder opals
The different color plays make Boulder Opals a popular gemstone for jewelry. They are mainly used for pendants for necklaces or bracelets, rings and bangles. If you are lucky enough to find two similar Boulder Opals, you can also have earrings made from them. As already mentioned, doublets can also be used for jewelry.
If you are looking for an individual piece of jewelry, the Boulder Opal is the right choice for you. Each of these opals is unique and invites you to look at the colors and patterns for a long time. As a gift, the opal is particularly suitable for those born in October. The Boulder Opal is (like all opals) the birthstone of October according to the American Gem Society.
Depending on the colors and preferences, Boulder opals can be set in silver, white gold, red gold or yellow gold.
Australia – the home of boulder opals
Boulder opals come mostly from Australia, where they were discovered by an Australian jeweler in 1875. Large quantities were soon being mined, mainly in the Queensland region.
Other deposits are found in Brazil, Honduras, Mexico and Canada.
Properties & most common cuts
Like all opal stones, boulder opal has a hardness of 5.5 to 6 on the Mohs scale. The scale ranges from one to ten, with one being for very soft minerals (talc) and 10 being for a very hard mineral (diamond).
Boulder opals are worked in such a way that the opalescence is accentuated. For this purpose, mainly smooth cuts are used, such as the cabochon cut. The shapes can vary greatly depending on the rough stone, from triangular to round and oval to drop-shaped boulder opals, there is a wide selection. Some boulder opals are offered as rough stones. These are mainly used as pendant stones.
