A black ring worn on the middle finger of their right hand is a common symbol of the asexual community. The material and exact design of the ring are not important as long as it is primarily black. The black ring is often associated with people who identify as swingers. However parts of the swinger community have taken care to inform people to not wear the black ring on the right hand, middle finger out of respect of the Asexual community. Plain black rings also coincide with the symbol ⚪ which symbolized asexuality and genderless. This symbol is also often written in black, simple because it's a common ink color.
The origin of the black asexual ring, as an asexuality symbol, can be found in this thread started in 2005.
|Your right middle means "currently single", the right ring means "currently taken" and since the left ring means "taken/married" in a permanent sense, then the next logical conclusion would be that left middle means "permanently single".|