The most popular precious metal type used in fine jewelry is gold. 18K gold tends to be more popular with Asians; 14K gold is purchased more frequently by Americans, and in Europe even lower grade alloys are used. Since pure gold (24K) is too soft for most jewelry, 18K gold (75% pure) and 14K gold (58.3% pure) provide the best combination of gold purity, durability and practicality. 18K and 14K gold can be manufactured in a range of colors, including yellow, white and rose. White gold is created by combining gold with white metal alloys such as silver and palladium and then typically, the mixed metals are plated with rhodium. Rose gold is produced in the same manner, but the ratio of copper alloy is increased.
Some gemstones, such as ruby, are thought to look best when set in yellow gold, and there are others, such as blue sapphire, which are often ideal for settings in white gold. White diamonds will look whiter when set into a white metal. There has definitely been a noticeable trend towards white metals in recent years for all varieties of gemstones, including diamonds.
White gold can easily be confused with another white metal known as platinum. Platinum is very popular for use with fine jewelry and is often reserved as being the most luxurious of precious metals. Unlike gold, platinum is strong and hard enough to be used in its absolute pure form, and you'll often see platinum jewelry stamped with "950 Platinum", indicating that it is 95% pure platinum. Platinum is usually mixed with 5% iridium, palladium or ruthenium.
Platinum is a very dense metal type and unbeknownst to many, the density is even greater gold. Considering platinum is used in a near pure form, when scaling piece-for-piece, platinum jewelry will be noticeably heavier than gold jewelry. Platinum is also much more rare than gold and so the price for platinum has been, on average, substantially higher over time. Only recently has the price for platinum dropped below that of gold's rate. Because platinum has higher density and the purity of the metal used for jewelry is greater than that of gold, and since the weight of platinum would be higher than the weight of 18K gold in any one particular piece, platinum jewelry will usually be much more expensive than gold jewelry.
Platinum for Jewelry
The color of platinum is whiter than that of white gold (lacking rhodium plating). But much platinum jewelry is also plated with rhodium to achieve the superb, highly polished presentation of rhodium. Some jewelry designers are now using a brushed or matte finish with un-plated platinum in their jewelry designs.
Platinum is highly valued for its incredible durability and strength. Although platinum can be scratched, it tends to not wear away, thus, platinum will usually outlast any jewelry composed of gold. Because platinum is so strong and stable after set in position, it is an ideal metal to be used as prongs that hold a gemstone in its setting.