Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of high-end jewelry peddler Tiffany (NYSE: TIF) were sparkling like diamonds today as investors pushed the stock up as much as 10% in intraday trading after the company reported strong second-quarter results.

So what: Tiffany was nice and helpful in giving an earnings release headline that summed up the situation very nicely: "Tiffany Reports Substantially Higher-Than-Expected Sales and Earnings Growth in Its Second Quarter." Whew! That makes my job easier.

Wait, you want more detail?

OK, fine. For the quarter, sales were up a whopping 30% to $873 million. Sales growth got a 6% boost from currency exchange and new stores, but same-store sales were still up a very-impressive 22%. Though the (non-Japan) Asia-Pacific region was particularly strong, sales growth looked great all over the world for Tiffany.

After adjusting for the costs of the company's headquarters relocation, second-quarter earnings per share were $0.86, a 58% jump from last year. Wall Street analysts were caught completely by surprise -- they were expecting sales of just $785 million and per-share earnings of $0.70.

Now what: What's better than one big shiny diamond? How about … two? The company complimented the show-stopping second-quarter results with a similarly strong full-year guidance boost. For the year, the Tiffany now expects to see earnings per share of $3.65 to $3.75 versus a previous range of $3.45 to $3.55. On average, analysts had estimated $3.56 in full-year EPS. The bottom line is expected to be driven by a soaring top line, which the company sees growing by "a high-teens percentage."

Can you put a price on this kind of performance? As investors, we have to. Using the midpoint of management's new guidance, Tiffany's stock is trading at roughly 19 times full-year 2011 earnings. Like the wares in its stores, that ain't cheap. Continued speedy growth could make that a worthwhile price, but investors will want to take a hard look at the numbers before mashing that "buy" button.

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