White gold is made up of a blend of gold and silver alloy material such as nickel, palladium or magnesium, having a value of 32.0 or less on the Yellowness Index.
More Info: The origins of white gold date back to the 1920s, when the blend was developed as a substitute for more expensive platinum. Many white gold blends are actually closer to a rose or yellow hue, something that is often remedied by the generally undisclosed use of a rhodium plating treatment of the jewelry piece(s). This can cause problems later if the rhodium coating starts to wear thin in spots, revealing the yellower gold color beneath it.
US White Gold Ratings Guidelines
For many years, the jewelry industry’s definition of what officially constituted white gold – a blend of gold and silver alloy material such as nickel, palladium or magnesium – was nebulous. But on March 7th, 2005, at an annual New York City trade show put on by the Manufacturing Jewelers and Suppliers of America (MJSA), the organization in tandem with the World Gold Council announced a new voluntary set of U.S. definition and ratings guidelines.
White gold was defined as having a value of 32.0 or less on the Yellowness Index, an ascending scale of measurement set up by the American Society for Testing and Materials (ASTM). Within this range, three grades of white gold were also specified: Premium (a Yellowness Index count of 19.0 or less), Standard (19.0 to 24.5) and Non-white (24.5 to 32.0).
White Gold Whiteness Index
In conjunction with this overall industry initiative, the Swizterland-based company GretagMacbeth announced the establishment of a White Gold Whiteness Index. This reference tool, intended for jewelers who do not use the advanced equipment of a spectrophotometer, allows them to determine the tier of white gold by comparing it with a naked eye chart of seven yellow gold samples.
“Guidelines to define the colour of white gold > Utilise Gold. Scientific, industrial and medical applications, products ,suppliers from the World Gold Council.” Utilise Gold Homepage > Utilise Gold. Scientific, industrial and medical applications, products ,suppliers from the World Gold Council. N.p., n.d. Web. 19 July 2010. http://www.utilisegold.com/jewellery_technology/colours/white_guide/.
“GretagMacbeth Munsell Color Assurance Lab Helps Jewelry Industry Make the Grade.” Marketwire: press release distribution, newswire, public relations,investor relations, breaking news, media monitoring. N.p., n.d. Web. 19 July 2010. http://www.marketwire.com/press-release/GretagMacbeth-Munsell-Color-Assurance-Lab-Helps-Jewelry-Industry-Make-the-Grade-662391.htm.
“What Is White Gold.” Utilise Gold. N.p., n.d. Web. 19 July 2010. www.utilisegold.com/assets/file/jewellery/technology/pdf/SFBK_WhitegoldChris%20Corti.pdf.