Gold vermeil is a type of gold jewelry made to last. The base metal is Sterling Silver which means your piece is made from precious metals only. A thick layer of gold is then electroplated over the base metal. While it may sound similar to gold plated jewelry, gold vermeil jewelry has a much thicker layer of gold. It's hypoallergenic, as it is made up of only precious metals (sterling silver), most people will have no reaction or issues with this type of jewelry.
Gold vermeil is more expensive than flash plated and gold plated jewelry because it uses sterling silver as the core material and uses a lot more gold.