Well if you type in avocadocentral.com You will be able to get into USA's Hass Avocado Board, which not only tells you everthing you would ever need to know about avocdos plus great recipes. eg HASS type avocado when ripe turns from Green to dark brown/black. Another variety is the FUERTE Avocado, if you type that in, you will get into their avocado site, Go to "Selecting & Handling" avocados of their site to find out how to choose Plus MORE great recipes BASICALLY: Signs of ripeness differ by variety, but all varieties yield to gentle pressure when ripe. To RIPEN quickly, put a hard avocado into brown paper bag with cut piece of apple & in a day or so it should be ready to use JUST BE AWARE in HOT WEATHER the cut apple will grow "fuzz" at room temperature.