Gold is a metal that will not corrode, rust, or tarnish, and, although it is very strong, it is also the most malleable of all metals.  The purity of gold is measured in karats, and in 24 parts.  24K gold is gold in its purest form; 12K gold is 50% gold and 50% alloy.  24K gold is very soft and is not ideal for jewelry and its everyday use and wear.  Alloys such as silver, copper, nickel, and zinc are added to gold for strength and color.  18k gold is durable yet has a beautiful appearance.  14K gold is very strong due to the amount of alloy included and still offers a beautiful shine.  This is the most common karat used in jewelry.  10K gold is the strongest of the karats containing 41.7% gold and a larger amount of alloy.

The color and karat of gold is established by the percent of alloy added to the gold.  For instance, 14K gold is an alloy consisting of 14 parts pure gold and 10 parts other metals.  When gold is alloyed with copper and silver the shades of yellow will differ.  The fewer alloys added, the brighter the gold's color will be.  If gold is alloyed with nickel or palladium, it turns to white gold.  Yellow gold and white gold normally share the same malleability and strength as each other.  White gold's color is comparable to platinum, but these two metals have separate properties and vary in cost.  White gold is usually plated with Rhodium, which is a form of the platinum family.  This is done to brighten the whiteness of the gold.

  

So what is rose gold?  Rose gold is created when copper is alloyed with pure 24-karat gold.  It varies so that the level of copper is anywhere from 25% to 66.6% within the gold.  Rose gold, like white gold, has the same strength and malleability properties as yellow gold.  It is stronger at 10K while softer at 22K, but, again, it is more valuable at the higher karat.  Rose gold is also called red gold and pink gold.

Platinum is relatively rare, and it is more valuable than gold.  It has become the most precious of all metals used in jewelry.  Its popularity has resurfaced in recent years due to its durability and nice white, silver-looking color.  Platinum is heavy and is offered in a purer form.  Small amounts of iridium and ruthenium, rare metals in the platinum family, are usually added to increase its hardness and durability.  Jewelry that is made is either 90 or 95% platinum and 10 or 5% alloy, respectively.  Platinum is not measured in karats like gold, but it is stamped differently.  The stamps, either PT or PLAT, identify the fineness of the platinum.  Jewelry settings made of platinum provide a nice accent to white diamonds.  Platinum has less chance of turning color than white gold due to its purity.  This metal is also an excellent choice for people who may be allergic to other metals such as nickel, which may be added to gold.

Silver is another popular metal used in jewelry.  It is bright and durable, and it is more abundant than gold.  It does not carry the popularity of gold or platinum, because it does tarnish and can lose its bright shiny color easily.  Because of this, jewelers will avoid using silver in a diamond setting or as fine jewelry.  However, in the early 19th century, white gold was not readily made, and platinum was not refined, so jewelers used sterling silver to set diamonds in.  Sterling silver is less expensive because of its flaws, and it is often identified by the stamp 925.