My husband bought my engagement ring from the Shane Company in Walnut Creek about five years ago, and we've been big fans of that store ever since. The store itself is small, and filled with cases displaying numerous pieces of jewelry that would likely suit just about any taste. They have diamonds, rubies, pearls, emeralds - just about any precious and semi-precious gem you could think of.
The employees are professional and well-dressed, and really seem to know a lot about jewelry. I'm impressed with them every time I take my ring in for a cleaning - they examine the stone, verify that it's the correct one based on my paperwork, and then have it cleaned while I wait. I rarely have to wait longer than five to ten minutes.
Their prices are also highly competitive; my husband did extensive research before selecting the Shane Company and said that their pricing undercut the 'mall shops' definitively. On top of that, he actually got to select the setting and the stone separately, so he was able to create the 'perfect' ring for me! I highly recommend the Shane Company for your jewelry needs.