I don't have a x-terra 30 but I do use a minelab, an I would say it can show up just about anywhere on the scale, my meter goes from - # which is iron to 550 which is silver an I have gold come in anywhere from 220-510. there are too many diffrent types of gold, sizes, shapes etc.I have 8k, 10k,14k,18k, small ear rings,some gold not marked,an none of them came in on a certain #. you can take 2 diffrent, 14k rings an they will read diffrent, because of the shape. Take a pull tab an get a reading, then give it a good twist, it will read diffrent, then break an still you get a diffrent reading. coins read the same, because they are the same, unless they are bent, or heavy crossion.