This surname of AMSTER is of Dutch origin (largely Jewish) and is a habitation name from the city in North Holland, so called from being built round a dam on the river AMSTEL. Many Jews settled in Amsterdam after being expelled from Spain and Portugal in the late 16th century, and they helped to make it a centre of the diamond-cutting trade. Before the First World War approximately 10 percent of the population of Amsterdam was Jewish. Amsterdam was chartered in the 1300, and joined the Hanseatic League in 1369. During the 17th century it prospered as a seaport; it gained significantly through Antwerp's loss of trade following the closure of the River Schelft under the Treaty of Westphalia in 1648. It became the capital in 1808. The name is also spelt AMSTERDAMER, van AMSTERDAM and AMSTERDAMKIS (East Ashenazic). Eleazar AMSTERDAM, was born in 1897, and lived in Cieszyn. Surnames as we know them today were first assumed in Europe from the 11th to the 15th Century. The employment in the use of a second name was a custom that was first introduced from the Normans. They themselves had not long before adopted them. It became, in course of time, a mark of gentler blood, and it was deemed a disgrace for gentlemen to have but one single name, as the meaner sort had. At first the coat of arms was a practical matter which served a function on the battlefield and in tournaments. With his helmet covering his face, and armour encasing the knight from head to foot, the only means of identification for his followers, was the insignia painted on his shield and embroidered on his surcoat, the flowing and draped garment worn over the armour. Over the centuries, most people in Europe have accepted their surname as a fact of life, as irrevocable as an act of God. However much the individual may have liked or disliked the surname, they were stuck with it, and people rarely changed them by personal choice. A more common form of variation was in fact involuntary, when an official change was made, in other words, a clerical error.