When the color of the mark is compared with the color of marks made by sample needles of known gold content, the proportion of gold in the coin is revealed.
وقد اكتشف الليديون ان احد انواع الحجارة المحلية السوداء المدعو ليدَيت (‏ او بازانيت )‏ يحل مشكلتهم .‏