Opal

Perhaps the most intriguing of all gems for its capacity to display multicolored flashes of light at the same time. When in movement, it gives the visual sensation of a living object. Australia and Brazil are the only important sources of precious opal. Production has been irregular; consequently, the finer qualities are quite rare. Color: white opal has a light body color. Black opal has a dark body color. The rare presence of the set of colors effect is what makes the opal precious. Set of Colors: the quality of the precious opal is determined by the quality and distribution of the multicolored flashes of light within each cabochon cut opal. Transparency: translucent to semi-transparent.

Price structure: top commercial white opals of 2 to 6 carats range from US$80 to US$250 per carat. Larger and finer stones can cost over US$300 per carat.