Lake County Diamonds
What you can find: Lake county "diamonds" (clear volcanic glass)
Ease of access: Easy, walking along roadsides
Equipment needed: Nothing but a good pair of eyes.
Safety considerations: Watch for traffic.
Where, exactly? Roadsides along Perini and Seigler Canyon Roads, near Lower Lake.
"Lake County Diamonds" are not true diamonds, or course, but rather a form of clear volcanic glass. Many people use them in jewelry as they are, or even facet the larger pieces. If you look hard enough, you can find some with a pale lavender cast to them.
The best place I have found to look for Lake County Diamonds is the roadsides along Perini and Seigler Canyon Roads, near Lower Lake. Just park your car in a pullout and walk along the roadsides, looking at any place with exposed dirt - road cuts, ditches, mole hills.
Please bear in mind that most of the adjoining land is private property. Do not stray into vineyards without permission from the owner [although if you can find a friendly vineyard owner, walking between the rows just after the soil has been turned over can be amazingly productive].
After a rain may be the best time to collect them, when the water has washed away the dirt that lays over them, but really you can find them any time of year - just make sure the sun is shining when you look. They're much easier to see when they sparkle in the sunlight.
They weather out of pockets in the nearby rhyolitic rocks, but there are plenty just scattered all through the soil around roadsides and vineyards.
I've been told they can also be found in the area of Middletown and Hidden Valley Lake, but I haven't gotten down there to look yet.
Once you've collected your Lake County Diamonds, take them home and put them in a bowl of warm water with a little bit of soap, and gently swish them around for a while to get all the dust and dirt off them and make them truly sparkle. Lay them out to dry on a towel.