This method works especially well with tomatoes, avocados, bananas, and cantaloupe. First warm the fruit by setting it in a sunny window or microwave it for 15 seconds on medium power. Put it in a paper bag with a couple of ripe apples and close loosely. You want the ethylene concentrated in the bag, but you also want oxygen to get in to speed ripening. Heavy is good .
Weight can be a good indicator of ripe fruit.
It generally means that the fruit is at least fully mature, which is a good start on the road to ripeness. A heavy tomato or grapefruit, for example, is usually a good one. If you have a grower nearby who allows you to pick your own or who's a conscientious producer who handles his produce well, by all means take advantage of that locally grown, just-picked ripe fruit. Your local county extension agent can help you find growers and farmers' markets. And speak up to the produce manager of your supermarket, too.