The opal is not very popular among Indians though it was known as a gem in ancient India. It is said that the Sanskrit word, 'upala' that means a precious stone evolved into opal, but others suggest that the Latin word for a gemstone, 'opalus' was the source of the present day name. Opals are available in most jewellery stores in Hong Kong and Singapore and are popular there.
Opal is not a durable gemstone as it is soft, sensitive to heat and dryness and is brittle. Its background colour ranges from white to yellow, red, pink, brown or gray. The brilliance of the flash of color - the 'opalescence' - and the colours themselves and their pattern influence the value of the stone. Opals that show large flashes and broad patterns are more rare and valuable than small patterns. There are three types of opals: precious opal, fire opal and potch, the common or unformed opal. Precious opal is graded according its background color and the intensity and size of the patches of flashing color. Most of these gems are white or light blue and green, but those that contain reds, oranges, and violets are more valuable. Black opal, that has a predominantly dark background but flashes color as it is turned, is very rare and so the most expensive of all opals. When it exhibits red and orange colours, it may well be as expensive as diamond, emerald, or ruby. Crystal opal or water opal, the next most costly type of opal, is transparent, with flashes, and is highly valued due to the brilliance of its colours and the fact that many layers of color within the stone come through.
Fire opal or cherry opal ranges in colour from colorless to yellow, orage and a deep red, with bright flecks of various colors. Jewelers offer it in faceted and cabochon cuts, with many fancy shapes. Most fire opal comes from Mexico and is sold for the color and clarity as faceted gemstones. It is not particularly expensive as it gets damaged easily.