Originally published on April 9, 2019
Solid gold is a term used to refer to various designations of karat gold. Pure 24k gold is actually too soft and weak to be used for jewelry production, thus the creation of gold alloys. Technically speaking an alloy is a mixture of metals (ex.: gold + silver + copper).
14k and 18k are the most commonly used in jewelry production. 14k gold is comprised of fourteen parts (58%) 24k gold and ten parts (42%) other metals. 18k gold is compromised of eighteen parts (75%) 24k and 6 parts (25%) other metals. The other metals added to gold help strengthen it and can dictate the color (i.e. yellow, rose and white).
Gold vermeil refers to sterling or fine silver electroplated with karat gold. The industry-set guidelines require that (1) the base metal is silver, (2) at least 10k gold is used for plating and (3) the plating thickness be at minimum 2.5 microns. Some gold vermeil jewelry has a ".925" or ".999" mark to denote the base metal is silver.
Gold filled is created by mechanically bonding karat gold and a base metal. The name can be misleading but think of it as a tube of gold that's filled with another metal, typically brass. To qualify as gold filled at least 5% gold by weight must be present. Often gold filled metals are stamped with a "1/20 14k" mark indicating 5% 14k gold.