If the dental crown is made entirely of gold, it is 24-karat gold. This is known as a full gold crown. If it considered a high noble alloy, it must have at least 40 percent gold, making it about 9.6-karat gold.
A high noble alloy consists of gold alloyed with other precious metals such as platinum or palladium. A noble alloy must be at least 25 percent gold, or 6-karat gold alloyed with a semi-precious metal. A non-noble alloy contains less than 25 percent gold alloyed with a metal such as chromium or nickel. Gold crowns are chosen for their beauty as well as their durability.