While doing research in a local newspaper for my ancestors in Harvard, Illinois, I found this interesting tidbit published in a 1904.
German Betrothal Customs.
When a maiden is betrothed in Germany she is called “bride” by her sweetheart, who addresses her thus until it becomes time to call her “wife.” Immediately upon betrothal the lovers exchange rings, which, if the course of true love runs smooth, are to be worn ever afterward until death parts them. The woman wears her betrothal ring on the third finger of her left hand until she is married, and then it is transferred to the third finger of her right hand. The husband continues to wear the ring just as the wife wore hers when she was a “bride,” so that one can easily tell at a glance if a man be or be not mortgaged as to his affections.
Source: "German Betrothal Customs," (Harvard) Herald, 6 October 1904, p. 8, col. 4.