So there are a few different things to know when looking at gold jewelry. It's not overly complicated though.
Basically gold plated jewelry is categorised by a thin layer of gold that has been electronically adhered to a base metal. Usually copper, brass or nickel.
Gold vermeil is when the gold is electronically adhered to sterling silver (925 alloy of fine silver and copper). You could also add the gold to fine silver, it's just not common as fine silver is so soft.
Gold leaf is different again. Very fine, almost tissue thin sheets of gold are adhered to the metal using a specialised process.
Gold filled is a term used to describe another variable. In this case there is much, much more gold covering the base metal.
Solid gold is still an alloy of metals but the majority of the mix is gold.
The different karat of gold tells us not only the alloy but also the strength and colour of the metal. A 10k gold piece will be a light yellow, where as a 24k item will have a deeper more intense yellow tone.
I've been using a pen method of plating sterling silver jewelry (you can use a bath which is another way.... maybe this is complicated). The pen process allows for more accuracy. I like to have lighter and darker areas of the pieces. Or perhaps just plate the top or sides.
This effect will be exacerbated over time as the gold plating does eventually wear or chip away (depending on how kind you are on your jewelry!). I love the idea of seeing the silver peaking out over time. The piece will actually evolve, with you, over time.
Of course you can choose to get it re-plated. And if you do want your plating to last then avoid putting your piece in water. And don't polish it with a polishing cloth.
Any more questions just zap me an email.