TIL that a wedding ring is placed on the left ring finger because in ancient times, people used to believe that this was the only finger where a vein connected straight to the wearer's heart. This vein was named 'vena amoris', the vein of love.

**Why do the Germans wear their wedding rings on their right hands?

It was the Romans who gave us this custom of wearing rings of love and marriage. But just like Prince William, most Roman men did not wear a wedding ring. Usually it was the Roman wife; either his free wife or his concubine. A concubine in Roman times was an ‘unofficial’ wife. Some Romans could not marry the women they loved because either her social standing was too low to consider, or they were already married or engaged to some other woman with a higher class and money. In ancient Rome you could divorce your concubine. A Roman could divorce his wife too, but to do so was very scandalous, and he would have to pay his wife a huge settlement and give back her dowry. When Roman women married, they were given iron rings (a precious metal back then) with the inscription “Pignus amoris habes” or “I have pledged my love to you”. The ring was a promise and the Roman women were given the ring in a ceremony after the groom received his dowry. 

Pope Nicholas the Great introduced the wedding ring in Christian ceremonies sometime around the year 850 A.D. as the “unending perfect symbol of God’s love”. By the 13th century, the wedding ring was integrated into the regular part of the marriage ceremony. The Catholic marriage ritual from the 13th century has changed little over the past eight centuries. Back then, church scholars had concurred on the thesis that the blood in the left arm flows to the heart first, and hence they concluded that if a wedding ring, blessed by God, was worn on the left hand would help make a bride be steadfast in her love, faithful to her husband, and a true servant of Christ. 

For the next three centuries everyone who could afford a wedding ring wore it on their left hand. It wasn’t until the 16th century when the Netherlands began to rebel against the Spanish throne for their independence. The Calvinist Reform Movement had spread from France to the Netherlands. It took the Dutch eighty years to emerge as an independent nation. It was the Dutch who started wearing their wedding rings on their right hands to show their disrespect to the Pope and the Spanish crown. To this day, this Protestant gesture is important to the Dutch, and it caused a slight scandal when Prince William-Alexander of the Netherlands placed the wedding ring on the right hand of his Argentinian Catholic bride Maxima.

Even though John Knox took the Calvinistic Movement to England and later Scotland, both the English and the Scots still wear their rings on their left hands. It's assumed they do this, because John Knox was not very successful with his Calvinistic movement. Scotland went back to being Catholic under Mary, Queen of Scots, and Henry VIII made the Anglican Church the Official Church of England.

This custom of wearing your wedding on your right hand to show you were against Pope and the Rule of the Vatican eventually found its way into Germany through Calvinism and Lutheranism. It was during the Reformation, that Protestant Germans began to wear their ring on their right hands to demonstrate who was Protestant and who was Catholic. There were even cases in the 30 Years’ War where Wallenstein, the Marshall for the Holy Roman Emperor, forced his soldiers cut off the right hands of all the married Protestant prisoners they captured. 

Although the Peace of Westphalia was signed in 1648 and finally allowed Protestants and Catholics to live side-by-side in a relatively peaceful harmony, the custom of wearing the wedding ring on the right hand as protest against the Pope’s power prevailed, since the German Protestants used to be in the majority. Today the number of Protestants and Catholics are almost even, but the majority of Germans wear their wedding rings on their right hands, even if they’re Catholic.**

/r/todayilearned Thread Parent Link - en.wikipedia.org