Tiffany Earnings Fall  CHICAGO (Reuters) - Luxury jeweler Tiffany   Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=TIF.N target=/stocks/quickinfo/fullquote"&gt;TIF.N&lt;/A&gt; on  Thursday said quarterly profit fell 26 percent, hurt by  lackluster sales in Japan and higher costs for precious metals  and diamonds.