Our next publication under the heading "Stone of the Month" is about October opal.
The word 'opal' comes from the Sanskrit 'upala', which is translated as 'precious stone'. The ancient Romans called it "eye-sight captivating" (opalus); the ancient Greeks called it "eye-striking" (ὀπάλλιος). Opals might be of virtually every colour -- white, black, pale or dark purple, blue, green, yellow and red. Opalescence is an optical phenomenon in which specific shimmers and facets are forming inside a mineral when the angle of light changes, making opal an opal. Opalescence can be spot, mosaic or zonal. When light passes through transparent spheres, it enters the crystalline grid and is deflected and broken up into the components, producing an iridescent effect.

Opal contains between 13 to 30% water, so it is prone to drying out, cracking and tarnishing. Black and blue opals have the most luminous flecks. They can be refracted and sparkle with flashes of red, green and gold. These opals are mined in Australia. Most noble (gem-quality) opals are mined in Australia, Mexico, Brazil, Guatemala, Honduras, Japan, Slovakia, the United States (Nevada), and there are small deposits in Russia (Kamchatka).

Indigenous Australians believed that a Creator had come to Earth many years ago to explain the significance of rainbows, sky and clouds. When he stepped on the Earth, the pebbles and stones under his feet became glossy and variegated. According to Japanese legends, at the time when all things were created, the Creator blessed the Earth and put a particle of the Sun into the rocks so that the soil would always remain warm and fertile. Modern opals were formed from this particle. The ancient Greeks associated the stone with Zeus' victory over the Titans, after which the Thunderer wept for joy. His tears transformed into opals.

Opals were first brought to Europe from India and immediately enslaved hearts of the high society as well as magicians and healers. This happened at the beginning of the 19th century. In the past, opal was considered a rare gemstone for which a very high price was paid. The stone was different from all other minerals. An unreal, unlike anything else, the shimmering gave it a mysterious and sacred feel.

These minerals are divided into noble and common. The noble ones are notable for their beauty; they fluoresce, have deep shades and are perfect for jewellery making. Common opals do not possess chiaro-oscuro effect, and after special grinding, are used as ornamental stones. In the last ten years, opals have become increasingly fashionable. Before that time, they were seldom used in jewellery art. First, because they are difficult to work with (they are not favorable for making fine jewellery). Secondly, for a long time there have been legends about opals bringing bad luck. In 2018, jewellery house Cartie introduced massive opal jewellery. Since then there has been a bull market for these minerals, with one brand after another incorporating opals into their collections. The opals are cut into plumpish or oval cabochons so that they radiate all the colours of the rainbow.

New photo album entitled “Opal – the mascot stone of October” is posted in the museum Photo Gallery.