Gold – one of the oldest precious metals gold can be mixed with other metals for different colors and karats. The USA National Gold and Silver Stamping Act regulates gold jewelry, and requires that it be marked with the karat weight and manufacturer. The higher the % of gold the more yellow in color and slightly softer the metal. 

These are the most common gold marks:

	18 K or 750 (signifying 75% gold)
	14K or 585 (58% gold)
	10K (42% gold)

Silver has been used for jewelry since 3500 BC when the Egyptians created ornaments. The word "sterling" is short for "Easterlings" a form of money used in 12^th century England. To be considered sterling silver an article must contain at least 92.5% silver. Look for "sterling silver" or "925" mark. Rich in luster silver tarnishes over time and must be periodically cleaned.

Platinum is very durable and has been used for fine jewelry since the 1880’s. Very popular until World War II when it was banned from jewelry use in favor higher priority military uses. It’s hypoallergenic. Look for a mark with "PT" or "Plat".

METAL AND DIAMOND MEASUREMENT. The Carat or Karat is equal to 200 milligrams or 1/24^th part of a pure metal in an alloy. The Dravidians of India first found diamonds in 800 BC. They weighed them on their scales against the seeds or beans of the carob or "carat" tree. Diamonds, the hardest substance known, were named by the Roman poet, Manilius, in 16 AD using the Greek word "adamas" meaning invincible.