By: Sharon Tanenbaum All that glitters is, in fact, not gold. Here's how to tell platinum from palladium and get the most out of your jewelry dollars. Even if you barely know a karat from a carrot, that shouldn't stop you from acquiring a shiny new bauble (or two). To get what you pay for, however, it helps to know a bit of jewelry jargon. For instance, what's the difference between 24- and 14-karat gold? And what's so "sterling" about sterling silver? Industry pros and top jewelry designers answer common questions about precious metals and compare the merits of the most popular types. Now you can be sure that your jewelry purchases are worth their weight in -- well, you know. In the feature story, Alex Woo's Sienna rings and circle necklace are shown, along with the white gold Narissa earrings as examples of quality jewelry.