Fine gold jewelry comes in several set varieties. The cheapest would be 10k gold which stands for 10 "karat". Gold sold in the United States would be stamped on it 10K to show the content. Beware of anything stamped with a 10C. Carat spelled with a "c" refers to diamond or gemstone weight. Karat with a "k" is for gold notation. Ten karat gold does not have the distinctive glimmer of higher Karat gold, however it is stronger, more durable and more scratch resistant. Gold is a very soft metal, so the higher the karat, the easier it will be for the patterns to wear off. If you are buying gold as a gift for a child 10k is a nice place to start. It can be set with a real gemstone, a large one if you buy semi precious stones, making the gift appear more "showy."
Semi precious stones come in many varieties. Garnet, is a translucent blood red stone reminiscent of a ruby. It does not have the cheery redness of a lab created ruby, but it is often set in Art Deco and Art Nouveau pieces quite beautifully. The semi precious green stone is a peridot, much lighter than an emerald. More expensive than a peridot and cheaper than an emerald are green amethysts and the rare green garnet. A blue quartz stone is less expensive than a light blue aquamarine, and so on. For each precious gem there is a slightly less expensive stone you can find in a cheaper class of gold that is still genuine and authentic and over time will hold value better than a lab created stone.
The next level of gold sold is 12k gold. Because it is still relatively hard, 12k and 14k are often used to make necklaces and chains. Rubies, emeralds, pearls and other fine stones are usually set in 14k gold and above. In the United States 14k is the norm as the highest level for jewelry making, however in Asia 22k and 24k are not unheard of. My relatives in Sri Lanka don't buy anything less than 22k. The Asian gold has a much deeper more beautiful color. Anyone who puts the two side by side will easily pick out the gold with the higher content. A bracelet made of 22k will dent easily, and carved patterns may wear off in time.
Some manufacturers in an effort to sell more jewelry have come up with options that make cheaper jewelry available. The first option is to substitute lab created stones for found or mined gems. A sales person will tell you that no one can tell the different, and that chemically the two are the same. You will notice, the price may be half or a tenth of real jewelry depending on the gold content. You won't have to look very closely to see how cheap a lab created gem looks. The color is cloyingly clear â€“ of course, because they are always "perfect." The red is too bright, the green too clear. These items will not go up in value. For what it's worth, buying craft fair jewelry from a well know artist, made of glass materials or clay will hold value better.
The next ploy is not really ploy, it is the relatively new practice of setting precious stones in cheaper material, such as silver instead of gold. This is not a bad idea. Real silver is very pretty. Generally turquoise, corals and pearls can be found set in silver. Recently even diamonds have been found in very attractive silver settings. Silver is a harder metal and will withstand wear. The only real drawback is that it will tarnish. Buy a polishing cloth when you buy the piece and rub it weekly to keep it nice looking.
"Gold plated" is a marketing ploy to make unsuspecting men think they are getting a really great deal on some gold jewelry. The truth is, gold "plate" is so ultra thin it wears off in a very short time from normal contact with skin oils. Some women I know protect the plating by coating the whole piece in clear nail polish. For what it's worth, you're better off buying something set in bronze, copper or silver because once the plating wears off, which it will, you are left with a really cheap looking piece. The underlying metal may be weak or dull. Having the plate wear off unevenly, which it generally does, makes the whole piece look awful.
A step up from gold plated jewelry is gold "filled" jewelry. To make it sound nicer the gold content may be advertised as 14k, pay attention! The difference between 14k and 14kgold filled is all the difference in the world. A "14 kt gold-filled wire is made by forming a tube of solid 14kt gold that is "filled" with a base metal. The gold is bonded to the base metal with heat and pressure. The base metal is also gold in color and is made up of almost the same mixture of metals (usually a brass alloy) used to bring 24kt gold down to 14kt, 10kt, etc. The exterior of the product is solid 14 kt gold and everything you can see or touch is a solid layer of 14 kt gold. This is why it will never tarnish, chip or wear off. The gold layer on gold-filled wire is approximately 100 times thicker than gold-plate as and is bonded with heat and pressure." So while, gold "filled" may be durable and chip resistant, it will not go up in value.
The final thing to consider when buying fine gold jewelry is the designer. A well known designer like Eddie LeVian may have more than one line of work. An authentic piece by him should be numbered and signed and include a certificate of authenticity. Such an item is heirloom quality and should be itemized on your homeowners or renters insurance policy. When he dies, it will probably go up in value much like a painting or a sculpture.