Great question Karenhoch! This is definitely the hardest of the limestones; however it is a living finish and will eventually scratch and stain over time. It would require to be sealed several times within a year and that still doesn't insure that it won’t scratch or stain. The sample that you are experimenting with may not be sealed or if it is sealed it is probably worn, which is causing the stone to get darker after cleaning up the olive oil. In the end these counter tops do take some work in keeping them in tip top shape. Always consult the stone vendor and they should be able to provide better tips on cleaning and caring for the counter tops.