Cash4Gold: How much is more?

American television is filled with commercials for companies that will turn your old gold jewelry into cash. You just send it in, and they send you a check, with no obligation to accept the deal.  It sounds straightforward enough, but the ads are a little misleading.  At the moment, Cash4Gold says it's offering a 25 percent bonus over its usual rates, presumably to entice consumers to try and grab that extra cash.  Yet in general, such claims are too vague to mean anything; you have to ask, "25 percent more than what?"  Cash4Gold never says what its regular rates are, nor do it say how often its regular rates change.  This is an important issue, since the price of gold has risen by 37 percent in the last year.  If consumers are getting 25 percent more than they did this time last year, Cash4Gold is pocketing the other 12 percent... but there's no way to know from the ads.