Materials

Metallurgy

The Romans were well-accomplished in the making of alloys, and could finely control the ratio of different components that went into their making. A much-used alloy was orichalcum, which was about four-fifths copper and one-fifths zinc and traces of tin and other metals. It was very ductile and had a colour similar to gold; in fact, a similar alloy is used in making imitation jewelry today.

Coin-making

Roman coins were officially made of silver but some were copper cores with silver plating. There were various techniques of plating - in the early empire, copper blanks were sandwiched between thin layers of silver sheet and heated for the bond to fuse. A simpler method was dipping copper coins in molten silver. However, by the 3^rd and 4^th centuries CE, they had acquired the knowledge that some acids etched copper but not silver. They used this method by creating the coin out of an alloy very low in silver content and then leave it in a bath of etching fluid. The copper in the outer layers would be dissolved by the acid, leaving behind the silver in a thin layer.

Other materials

The Romans, like most other people of their time, wore jewelry. While their choice of precious stones was nothing new, they succeeded in imitating some, especially emeralds, with great care using coloured glass. They also introduced yet another method of plating cheap metals with gold to improve their appearance. This was done by first coating the piece with an amalgam of gold and mercury (an amalgam is an alloy of mercury)  and then heating the piece. The mercury readily melted away leaving behind the gold in a fine finish.

The Romans used glass for windowpanes. Sheet glass for these panes was created by blowing glass cylinders and then splitting them lengthwise while the glass was still soft. The glass was often frosted by rubbing one side with sand.