14 DAY TRIAL // Thanks to efforts by scientists at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and a consortium of Australian Opal miners (Opal Producers Australia Limited), we now have a new technology readily available that can classify and grade opals automatically, through image analysis. The innovation was unveiled at the 2009 National Council of Jewellery Valuers forum, held in Sydney, Australia. The device has been dubbed the Gemmological Digital Analyzer (GDA), and CSIRO Mathematical and Information Sciences image analyst Leanne Bischof is one of its creators.
According to the expert, opals are among the most difficult-to-grade stones, largely because of their unique range of color characteristics. “Qualities such as 'flash', the way an opal reflects light and color as it is rotated, can vary with human eyesight and lighting conditions. A person's judgment of an opal's colors, the brightness of those colors and the area each of them covers is a really difficult task, even for a skilled opal assessor. You really need objective image analysis and automation to assist with that,” she says of the GDA.
Working together with Australian company Applied Robotics, and taking into account the professional expertise of more than 60 opal industry professionals, CSIRO was able to develop a working GDA prototype, which automates the opal grading process. The powerful image analysis system that gives the system its reliability is “powered” by intricate mathematical algorithms, which were designed in such a manner that they incorporate all the traits that people look for when assessing an opal's value. The new machine takes about 871 images of each stone it analyzes.
The samples are set on a tray inside the system, which is able to rotate 360 degrees horizontally, and has a 90-degree vertical tilt. Color, clarity, carat, cut, and character are among the analyzed aspects of each stone. All these data, together with a preliminary and summary graph showing proportions of the opal's colors are then fed into a computer, which processes them based on the mathematical algorithms that have been programmed into it.
“We wanted to create an objective grading system that would improve the demand for and value of the Australian Opal industry, giving miners a fair price and consumer's confidence to trade with grade quality assurance. This will be an independently-graded Australian opal product, which we will brand as Opallia,” says Peter Sutton, who is the director of Opal Producers Australia Limited, and also a Lightning Ridge Opal miner.
