For Europe and the Mediterranean that is close. The end of the Western Roman Empire in 476 AD marks the start of the European Middle Ages, although there were never any abrupt, major changes to most peoples' lives at the time.
I really don't know, they open the top, put in coins/jewelry, turn it on and it gives a reading of what metals are contained in the coins/jewelry and what percentage of each of the metals contained in the coin/jewlery is. They put in my coin and the readout said 89% silver. I had a $5 gold Indian that I knew was counterfeit and they put that in and the readout said copper and zinc. The next time I go to the store I'll get more information, but I do know they said it was very expensive, but in the long run it has been worth it. They know exactly what the jewelry and coins are composed of and with counterfeits getting better, it has saved them from making very expensive mistakes.