Gold lends itself to the manufacture of decorative articles because of its great resistance to corrosion and tarnish and its ease of working. Impurities are added to the gold used for jewelry to impart the desired color to the metal and to harden it. In the past white gold was produced by the addition of palladium to gold, but it is now manufactured from a gold-nickel alloy base. Gold alloys containing copper are red or pink in color and may be used for contrast in jewelry. The addition of silver to gold to form an 18 kt alloy gives a greenish color to the gold.
Gold occurring either as native metal or a simple salt is very easily detected. For milligram amounts, gold may be precipitated as the metal from solutions using any of a number of reducing reagents, such as hydroquinone, and subsequently identified by its characteristic metallic gold color.
USE OF COLOR AND LETTERING STYLES Most charts use color to emphasize various features. NOS charts use five multipurpose colors in either solid color or tints—black, magenta, gold, blue, and green.
Gold lends itself to the manufacture of decorative articles because of its great resistance to corrosion and tarnish and its ease of working. Impurities are added to the gold used for jewelry to impart the desired color to the metal and to harden it. In the past white gold was produced by the addition of palladium to gold, but it is now manufactured from a gold-nickel alloy base. Gold alloys containing copper are red or pink in color and may be used for contrast in jewelry. The addition of silver to gold to form an 18 kt alloy gives a greenish color to the gold.