Hello! I use Grade A or as labeled on the can as 100% Olive Oil. Extra Virgin and Virgin olive oil is the first pressing of the olives. The virgin oils are more valuable for cooking and consuming since they contain more valuable nutrients, minerals, vitamins, etc.. You can use them for soaping but from my reference books they make your soap batter very slow to come to trace and cure time is extended longer. The cost is also a factor. Grade A oil is not as costly and behaves more in soaping; reasonable trace times and curing time. Pomice olive oil is the last pressing of whatever remains of the olives. There is speculation that chemical solvents are used to help in this extraction. Also, this grade of oil speeds up trace time - sometimes too much. It is a popular soaping oil if you become more adapted of its behavior.
Please note: Always try to find an honest to goodness true supplier of 100% olive oil. Some unscrupulous businesses combine other liquid oils to lesser percentages of olive oil and market them as real olive oil. These added oils messes up the soaping calculations when making soap. Good suppliers will supply good restaurants with 100% real olive oil.