The high quality of extra virgin olive oil is determined by several factors, including the characteristics of the olives, the timing and method of harvesting, and the processing and storage conditions. The following are some of the main characteristics of high-quality extra virgin olive oil:

1. Fruity aroma: A high-quality extra virgin olive oil should have a fresh and fruity aroma that is indicative of the type of olives used.
2. Bitterness and pungency: A slight bitterness and pungency in the aftertaste is a sign of high-quality extra virgin olive oil, indicating the presence of healthy polyphenols and antioxidants.
3. Low acidity: Extra virgin olive oil should have a free acidity level of less than 0.8%, which indicates that it was made from healthy olives and processed correctly.
4. Freshness: High-quality extra virgin olive oil should be consumed as soon as possible after the harvest, to ensure that the flavors and health benefits are preserved.
5. Color: The color of high-quality extra virgin olive oil can vary depending on the type of olives used, but it should be bright and clear, with no cloudiness or sediment.
6. Origin and traceability: High-quality extra virgin olive oil is often produced by small or artisanal producers who are passionate about their product and can provide information on the origin and processing of the oil.

Overall, high-quality extra virgin olive oil should have a complex and well-balanced flavor profile, with no off-flavors or rancidity. It is often used as a finishing oil to add flavor and complexity to dishes, or as a healthy and flavorful ingredient in dressings, marinades, and other recipes.