A lot of people get confused about the term "precious metals" when it is used in jewelry. It simply means metal that has a significant monetary value in and of itself, not just for "art". Most Precious Metals were used AS money at some point, and in many cases used to back the value of money when printing made paper money possible.
This doesn't mean that good jewelry cannot be made from less valuable metals, of course! I have made a lot of very nice pieces in copper, and lesser metals are often combined with precious metals for artistic reasons. However it pays to know a bit about the labeling, and uses, of previous metals.
The better known precious metals are gold, and silver.
Is it real? Sometimes you see labels on things that say "gold" but they are not real gold. Usually these items are just gold colored. Every now and then you will see something labeled gold, with some kind of additional word, like "jewelers gold" or "filled" or "plated". This can be very different things....
Different countries have different laws about gold, and different expectations.
In the USA most jewelry is 14k gold, or just over half gold and just under half other metals. These other metals are used to give the gold more hardness and scratch resistance.
Depending on what "other metals" are used you can get different colors of gold. For example: White Gold is admixed with a white metal... often nickel. the problem is that many people are allergic to nickel and can react very badly to it. White Gold can also be made by admixing other metals, like palladium, but its a bit more expensive. If you are nickel sensitive, always ask what metal was used in your white gold!
Because gold is expensive, people often use gold plate. Gold plate means a THIN layer of gold on top of a less expensive metal (usually brass). Gold plate can chip, or peel, if not cleaned carefully, or if it gets scratched, and the metal underneath can often cause irritation. People who are sensitive to "base metals" like nickel, should probably avoid gold plate.
Gold-filled, however, is very different. Instead of a thin coating of gold, like gold plate, a gold filled item is a thick hollow tube of gold, that was filled with another metal (often brass, yes). It is hundreds of times thicker than gold plate and not very prone to scratching or peeling. It can be very difficult to tell a "14k Gold-filled" item from a solid 14k Gold item.
(For a Gold Filled Item the abbreviation "GF" must be added, so an item stamped "14k gf" is gold filled)
Vermeil is a special case. Vermeil is a gold plate (a thin layer of gold) on top of Sterling Silver! This is the exception to the rule about not wearing gold plate if you have metal sensitivities. As long as you are not sensitive to Sterling Silver, of course!
With Silver you are usually only dealing with a couple of basic questions:
Is it really silver? or just silver colored?
Is it Sterling Silver, or Fine Silver?
Anytime you see a place name be very wary. Its not always fake, sometimes its a marketing question, but "German Silver" is another name for nickel, and "Hill Tribes Silver" means it was made in a specific place, out of real silver! So if you see a place name on your "silver" always ask what it means!
Sterling Silver is not pure silver; A lot of people get confused by that. Sterling silver is .972 silver, and .028 something else (that's not a lot). Usually the silver in this mixture is mixed (alloyed) with copper. Now i love Sterling Silver, but as a jeweler the copper sometimes causes some issues, like making it a bit trickier to solder. Sometimes you get some metals mixed into silver, sold as "Sterling" that shouldn't be there, like nickel. This is why i always sourced my sterling silver very carefully, to make sure it was what it should be!
Sterling silver is also often plated with another metal to stop tarnishing! this is different than "silver plate" (see gold plate, above) its real sterling silver plated with a silver colored metal that doesn't tarnish...
now that silver prices are climbing, we have "silver-filled" on the market!
No one used to make silver filled wire or jewelry, it just wasnt worth the time, but now that silver prices are so high we are seeing silver filed on the market. Silver filled should also be labeled (like "sterling silver filled") but as with gold, when you buy something second hand, you never know.
Fine silver, my favorite, is .999 pure silver. Because it has no copper admixed it doesn't tarnish as much, and it behaves better when you heat it to make head pins. Some people who react to Sterling Silver can wear fine silver, so its worth giving it a try.
There are other precious metals of course.
Platinum is the one most people know. Its very hard to work, so most small jewelers don't handle it, but its fairly non-allergenic and sturdy.
Aluminum used to be a precious metal, did you know that? It was worth more than silver until a new technique made it possible to extract the ore easily. That dropped its price so much that now its used instead of "tin" foil!
There are many other metals used in jewelry work: Niobium, copper, brass, bronze, pewter, and more. There is nothing wrong with using a less valuable metal in jewelry! (or no metal at all) I have several of my favorite pieces that were primarily made in copper and brass.
I just make sure the ear wires (the part that goes through my ears) is silver or gold, or stainless steel. After all, that's the only part of an earring that actually has to touch my ears!