Excerpted from "Fabulous Finds" by J. Lee Drexler and James R. Cohen. Available from Quill Driver Books, an imprint of Linden Publishing. Copyright © 2011 by J. Lee Drexler and James R. Cohen
Jewelry of all types, particularly gold jewelry, is one of the most popular things to buy personally and as gifts. Unfortunately, in the vast majority of jewelry purchases, people pay far too high a price. The average jewelry sale is figured at "triple keystone" price, which is what the trade calls triple cost. In other words, if a jeweler shows you a book with an item listed at a price of $3,000, he probably has paid $1,000 for it. He might offer you a "bargain" of a 20 percent reduction bringing the price all the way down to $2,400. Don't feel that you're taking unfair advantage of him, as he will be making $1,400 on an item he purchased for $1,000 -- a profit of 140 percent.
It is important to know certain basic things about gold jewelry. If jewelry is stamped "750," it means 750 parts gold with 250 parts alloy, so it is 75 percent pure gold. That is the same purity as 18-carat gold. Gold marked "585," or 14-carat, is about 60 percent pure gold. Similarly, "375," or 9-carat gold are both 37.5 percent pure gold. Although in England they sell 9-carat gold and think highly of it, in the U.S. it is considered just costume jewelry, and is therefore not a good investment. You would probably never be able to resell it for anywhere near what you paid for it.
Generally you can expect to sell a piece of jewelry for the pure gold weight. To figure out the base value of your gold jewelry, you need to weigh it on a jeweler's scale. Whatever it weighs, you must make deductions for the amount of alloy in the gold: for example, 18-carat gold is 75 percent gold, so deduct 25 percent from the value to figure its gold weight. So, if the current price of gold is $1,000 an ounce, and an 18-carat piece weighs four ounces, the value of the pure gold in the piece is $3,000, the price that you could expect to receive if you sold it.
On the other hand, if you buy the same 18-carat bracelet on Forty-Seventh Street, you should be able to find a shop that would sell it for approximately $4,000, about a third over its weight. Outside the jewelry district, triple keystone is the standard, and you should expect to buy the same pieces for approximately $9,000. None of the above holds true for pieces being made today by top name designers like Bulgari, Buccellati or Cartier, where a gold bracelet that has three ounces of pure gold could see for as much as $30,000 (ten times its weight). Of course, there are particularly well-designed pieces by famous jewelers, so you are paying a very substantial premium for the design and for the "name." But if you were to sell these designer pieces, while you will definitely get some premium over weight, it will not be vastly more than the weight that an ordinary gold piece would bring.
Be sure to click through HuffPost Home's slideshow to see ordinary items in your house that could be worth big bucks.