The Play of October Colours
 Originating from the Greek word "Opallos", meaning to determine a change of color, the Opal strives its way amongst the most precious gemstones. Pliny the Elder (23-79 AD), the author of the first existing encyclopedia, who was a Roman historian, shares an opinion of the Opal as "the brilliant purple of the amethyst and the sea green color of the emerald, all shining together in incredible union".
The Romans had been wearing Opals for centuries and had taken them into consideration of symbol of hope and purity, while for the early Greeks they were believed to boost the powers of foresight and prophecy. It is of utter interest that an overall perception of Opals in terms of defensive measures has been persisting throughout ancient times. The practice of dropping an Opal stone in glass of wine prevented the person, who'd consume it, of eventual poisoning. By a certain chemical reaction, Opal forms a diffuseness within its surroundings and as a result an amorphous white cloud is formed circa the Opal stone in the bloody-red wine.
Opal is made up of amorphous silica spheres with 5-10% water inside their structure (an effect called Opalescence) comprising of pyramidal arranged rows of tiny silicon dioxide spheres. Namely to their water content, Opals are highly sensitive to sudden changes in temperature, and being exposed to suchlike conditions they are probable to take deteriorating terms.
The finest and most precious representatives are the so called 'Boulder Opal', most of which samples possess an undulating surface of "hills" and "valleys". Thanks to their ironstone inclusions, the Boulder Opals allow unusual and complex manipulations to their shape with a perspective to adopt popular, avant-garde and highly progressive design. Some of the shapes can be circular or round, teardrop, square, rectangle, and triangle.
Because of the fact that Opal displays a whole rainbow of colors, it could suit and be appropriate for any outfit in different colours. That is the reason why its most usual form is a dome shape. Common pieces of jewellery that bear Opal stones are Opal brooches, Opal pendants, and Opal earrings, and last Opal necklaces. Some Opals are distinctively designed into beads, even though rare, which adds up contribution to the brilliance of the woman's look.
Being relatively soft and fragile stones, Opals tend to be roughly treated with a stratification of layers in doublets and triplets, which on the other side is perfect measure for creating Opal rings. Size is also a factor with the carat price for larger stones accelerating accordingly.
The Opal is a mineral with high variation in colour. A special phenomenon for the Opal are the produced spectral colors due to the size of the spheres within the stone. This extremely special characteristic of the Opals is called "play of colour". A splendid beauty could be derived from this effect, which is quite similar to the iridescent rainbow colors displayed on a soap bubble. A certain range of prismatic colors is determined by the size of the spheres. The brighter the "play-of-colour" the better and more precious the Opal. The "play-of-colours" is best described in terms of brightness, spectral range, saturation, pattern, consistency and directionality. The play of color is the way in which colors change as an Opal is tilted, moved or rotated in different directions.
Emphasizing and accentuating the brightness, black is considered the most valuable colour for an Opal stone. Being crystal or opaque, the black Opal presents best contrast on a very dark background. Just the opposite, the semi-black Opal takes its most beautiful appearance at a light background. Other diversifications of colour are also the Light Opal, the Crystal Opal, the Fire Opal (also known as Cherry Opal). Another of the Opal's characteristics is the 'skin-to-skin' Opal, meaning the most of its appreciation, from top to bottom, evaluating a piece of Opal or just a cut of it.
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