Get a scale dude, there is no way to accurately eye ball a gram. It could be in one rock the size of a quarter, or a light fluffy powder that fills up a dime bag or two and they could weigh the same.... or be grams apart from each other
Plus, eye balling doses can be quite hazardous to your health
If you are unsure of the weight, then getting a scale is necessary. Otherwise it will be hard to determine how much you have exactly and how much you will dose.