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 online jeweler Blue Nile (Nasdaq: NILE) sank 11% Thursday after its quarterly results and full-year outlook easily missed expectations.

So what: Blue Nile's fourth-quarter whiff was so big -- EPS of just $0.30 versus the consensus $0.42 -- that Wall Street analysts have no choice but to significantly cut their price targets on the stock. Weak high-end diamond demand, coupled with rising input costs, is naturally triggering fresh concerns over the company's long-term profitability.

Now what: Looking ahead, Blue Nile now sees full-year 2012 EPS of $0.70-$0.85, well below the average analyst estimate of $1.09. "The fourth quarter was challenging for Blue Nile, with weakness in demand from our high end diamond customers and some of our international markets, as well as the continued impact of inflationary pressure on commodity costs," said CEO Vijay Talwar. "While we managed the business through these headwinds, we implemented components of a new strategy designed to accelerate growth." When you couple the trends working against Blue Nile with its still-lofty P/E, however, I'd wait for an even bigger pullback before betting on that growth.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.