Fine Sterling Silver and Raw Diamond Engagement Ring. Three completely raw, fresh from the earth, California; Lake County Diamond set in solid sterling silver. Stone: California Diamond Band: Sterling Silver Ring band size is available in 3 to 13 US California - Lake County Diamonds are Quartz Science has its own explanation for these wonders of nature. Lake County has been the scene of incredible volcanic activity throughout its ancient past. Mount Konocti, the area's defining landmark, is a dormant volcano where past lava flows of magma and basalt were contained under enormous pressure with temperatures of not less than 1,112 Fahrenheit. Heat and pressure resulted in the formation of beta silicon dioxide crystals - Lake County Diamonds - of unsurpassed clarity and the finest optical quality. Lake County Diamonds are mostly clear and very hard, ranking from 7.5 to 8 (and possibly as high as 9) on the Mohs Scale. They have been used commercially and industrially, but are in greatest demand as semi-precious gems. Lake County Diamonds may be set uncut for a rough natural look, or faced to set off their inner fire which compares in brilliance to African carbon diamonds.