Gold
Pure gold is soft and isn't practical for daily wear. Other metals are mixed with it to make it more durable (and to lower its cost). Adding other metals to the mix allows metallurgists to change the color and hardness of gold.
Palladium or nickel can be added to create white gold. Adding copper produces a rose or pink tint, while silver gives gold a greenish cast.
Gold Carat
When metals are added to the gold the result is a gold alloy. We often see the mark-âKâ in our gold alloy jewelry. The K stands for karat, the system used to state how much pure gold is found in an item.
24K gold is pure gold.
18K gold contains 18 parts gold and 6 parts of one or more additional metals, making it 75% gold.
14K gold contains 14 parts gold and 10 parts of one or more additional metals, making it 58.3% gold.
12K gold contains 12 parts gold and 12 parts of one or more additional metals, making it 50% gold.
10K gold contains 10 parts gold and 14 parts of one or more additional metals, making it 41.7% gold. 10K gold is the minimum karat that can be called "gold" in the United States.
9kt gold contains 375 parts per thousand parts, making it 37.5% pure gold.
Solid gold is a term that can be used to describe an item that's at least 10K (in the US) gold all the way through. Even though it's a gold alloy--18K, 14K, or anything down to 10K--it can be called solid gold.
Solid gold is durable, so it is a better choice for jewelry you'll wear regularly. If you have allergies to nickel or other metals, choose items that have high gold content, such as 18K or 22K gold jewelry.
Gold Color
White Gold
Nickel can be mixed with gold to create a white (or gray) color; it can cause dermatitis in people who are sensitive to nickel.
Palladium is another metal used to create white gold alloys. Related to platinum, it is more expensive than nickel.
Rose or Pink Gold
Copper is added to make gold-colored alloys, but additional copper creates pink and rose tones--the more copper, the deeper the effect.
Green Gold
Greenish shades are created by adding silver to gold.
Black Hills Gold
Black Hills Gold jewelry is a good example of colored gold alloys. Most Black Hills Gold jewelry uses 10K or 12K gold alloys in shades of yellow, pink, rose, and green.
Other Kinds of Gold Jewelry
Gold Plated Jewelry
The gold layer in gold plated jewelry is typically thinner than the gold in gold filled jewelry, so it usually wears away more quickly. Plating is done in different ways.
Gold Filled Jewelry
Newer gold filled items have markings that indicate how much and what type of gold was used for the layer.
Gold filled or plated jewelry is suitable for jewelry that you wear occasionally. Everyday use would eventually diminish the gold layer, exposing the metal below, which might stain your skin or cause an allergic reaction. For pieces that will last a lifetime and beyond, buy the highest quality gold your budget allows.
Platinum
Content and Platinum Marks
Platinum is a rare precious metal that's used to create fine jewelry. Its heavy weight and durability make platinum a metal that will not wear away with constant use. Platinum holds fine gemstones firmly in place for the life of the jewelry when used as prongs and other setting components.
Platinum's natural white luster provides a rich backdrop for pearls. Platinum make the pearl jewelry more stunning and elegant.
The Platinum Group of Metals
Six related metals belong to the Platinum Group of Metals, or PGM:
Platinum
Iridium
Palladium
Ruthenium
Rhodium
Osmium
Jewelry that contains at least 950 parts per thousand of pure platinum may be marked or described as "Platinum"
Jewelry that contains 850, 900 or 950 parts per thousand of pure platinum may be marked "Plat" or "Pt" if a number is used in front of the term to disclose the amount of pure platinum in the mix, such as "850 Pt", " 900 Plat" or "950 Pt".
Jewelry that contains at least 950 parts per thousand of platinum group metals, with at least 500 parts per thousand of the total pure platinum, may be marked as platinum as long as the numbers of each metal are disclosed. For instance:
"600 Pt. 350 Ir." or 600 Plat. 350 Irid." for 600 parts pure platinum and 350 parts iridium
"550Pt. 350Pd. 50Ir." or "550Plat. 350Pall. 50Irid." for 550 parts pure platinum, 350 parts palladium and 50 parts iridum
Sterling Silver
Silver is a soft metal in its pure form, too soft to be used for jewelry and other items, so it's mixed with other metals to make it more durable. A popular silver mixture is known as sterling silver.
The minimum silver content is often stated as 925 parts per thousand of pure silver, so you might see the figures 925 or 92.5 used to mark silver content.
Gold