Here's a table of the top online jewelry retailers. Note the positions of publicly-traded companies Tiffany & Co. (NYSE:TIF), Blue Nile, Inc. (NASDAQ:NILE) and Odimo Inc. (Nasdaq: ODMO) and Zale Corp (NYSE:ZLC).
Click on the table to enlarge:
The problem with this data is that it's outdated -- 2004 sales, published in 2005. Are more recent data available for 2005 sales? Not clear, as multi-channel retail public companies don't always break down their online sales in their public filings.