Science, Tech, Math › Science Composition of Gold Alloys in Colored Gold Jewelry Composition of Gold Alloys in Colored Gold Jewelry Share Flipboard Email Print Dorling Kindersley / Getty Images Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate by Anne Marie Helmenstine, Ph.D. Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. Updated January 27, 2019 When you buy gold jewelry, it isn't pure gold. Your gold is really an alloy, or mixture of metals. The purity or fineness of gold in the jewelry is indicated by its karat number -- 24 karat (24K or 24 kt) gold is as pure as gold for jewelry gets. Gold that is 24K is also called fine gold and it is greater than 99.7% pure gold. Proof gold is even finer, with over 99.95% purity, but it is only used for standardization purposes and is not available for jewelry. So, what are the metals that are alloyed with gold? Gold will form alloys with most metals, but for jewelry, the most common alloying metals are silver, copper, and zinc. However, other metals may be added, especially to make colored gold. Here's a table of the compositions of some common gold alloys: Gold Alloys Color of Gold Alloy Composition Yellow Gold (22K) Gold 91.67%Silver 5%Copper 2%Zinc 1.33% Red Gold (18K) Gold 75%Copper 25% Rose Gold (18K) Gold 75%Copper 22.25%Silver 2.75% Pink Gold (18K) Gold 75%Copper 20%Silver 5% White Gold (18K) Gold 75%Platinum or Palladium 25% White Gold (18K) Gold 75%Palladium 10%Nickel 10%Zinc 5% Gray-White Gold (18K) Gold 75%Iron 17%Copper 8% Soft Green Gold (18K) Gold 75%Silver 25% Light Green Gold (18K) Gold 75%Copper 23%Cadmium 2% Green Gold (18K) Gold 75%Silver 20%Copper 5% Deep Green Gold (18K) Gold 75%Silver 15%Copper 6%Cadmium 4% Blue-White or Blue Gold (18K) Gold 75%Iron 25% Purple Gold Gold 80%Aluminum 20% Continue Reading What Is the Chemical Composition of White Gold? What Is Electrum or Green Gold? Places You Can Find Gold to Recycle, Use, or Sell Do You Know What Makes a Ring Turn Your Finger Green? A List of Precious Metals and What Makes Them Valuable Interesting Facts About Alloys, Which Are Blends of Metals Do You Know These 10 Fun Facts About Gold? Know Your Elements: Gold Facts What Is an Alloy? 10 Fun and Interesting Titanium Facts What Quality Marks Say About Your Metal Jewelry What Is a Eutectic System? What an Amalgam Is and Its Uses Copper Alloys List Are Olympic Medals Made Out of Pure Gold? What Are the Composition and Properties of Bronze?