5/5
I love this shop. Museum quality displays are everywhere you look. And the folks who work here are invariably courteous and helpful. Gaumer's has what you are looking for - whatever your interest in stones, fossils, minerals, mining, jewelry and more. They also provide repair services, and have a fantastic collection of stones and minerals from around the world if you are looking for something to cut & polish for yourself. There is a book section with trail guides and "how to" books, as well as a small collection of old (some out of print) books and reference materials that you can browse through to find just what you are looking. They have supplies for cutting, polishing, tumbling, assaying and more, and their prices are always reasonable. Some of the rarer stones seem a little pricey until you start comparing...
Even if you just want to look around at pretty rocks and fossils you definitely need to add Gaumer's to your itinerary. It has super easy access off and on the freeway, and is a short walk (shorter drive) from restaurants and shops, including a modest sized Tesla Supercharger station.
AND... they will be open on select Saturdays for the holiday season!
Woohoo!
P.S. Don't forget to stop and look at the beautiful petrified wood log in the entry foyer!