Olive groves line the rocky hillsides of Italy and the Mediterranean coast. For millennia, the region has produced gorgeous olives (they were a favorite street snack in ancient Rome) and olive oils (tools for making olive oil that date back 4500 years have been found in Crete). The average age of southern  Italian olive trees is between 300 and 600 years -- the olive tree doesn't even begin producing edible fruit before its 25th year. Today, Spain, France, Greece, Italy, and California all produce high quality olive oils from those old olive trees.

Olive oils come in various grades and intensities. Hand-culled olives for the highest quality oil must be pressed quickly -- within 24 to 48 hours for best results. The first pressing happens between great rollers of stone or steel. Stone is best because it is softer than steel and it doesn't conduct heat. The first oil produced is called "extra-virgin olive oil." The mashy pulp left over is then mixed with hot water and processed to make second and third press oils. The state regulates the labeling of olive oils according to the level of acidity. "Extra virgin" has less than 1 percent oleic acidity and less than 0.5 percent in the very best oil; "superfine virgin" can have up to 1.5 percent acidity; "fine" or "regular virgin" ranges from 1.5 to 3 percent acidity; and "virgin" or "pure" has up to 4 percent. Any oil with an acidity level higher than 4 percent is only good for lamps. This classification, however, can be misleading because modern chemical processing can greatly reduce acid levels no matter what the quality of the oil. A lesser oil can processed to a .05 percent acidity level, be packaged as "extra virgin," and still taste terrible. One clue to look for -- if a label reads "cold pressed" then it has not been refined and is of a higher quality. It will also be of a higher price.