The purpose of most grammatical comma rules it to provide clarity. Sometimes, there is not a specific rule that creates the clarity your words need to make complete sense to your readers. Without this clarity, what you are trying to say is lost. When you encounter a situation that you cannot apply a specific rule, but you feel a clause or phrase is confusing, use a comma to make your words more clear. Consider the following examples:
In the above example, the missing comma in the first sentence leaves some confusion. Even through “to Sharon” is an introductory prepositional phrase that is less than three words (see Introductory Elements section of the comma guide for more information), leaving it out makes it unclear whether Sharon is the doctor or the sentence is about Sharon’s thoughts on the doctor.
In the above example, omitting the comma in the first sentence makes the sentence confusing, as it reads that the referee’s call both singled her out AND prepared her for the penalties. By including the comma, the meaning is clear: she felt the referee’s call singled her out, so she prepared for the penalties associated with the call.
There are some cases where using or omitting a comma implies that you are writing about only one or more than one thing. Consider the following examples:
Using commas to offset the title of the article indicates that only one article was written by the author. Likewise, offsetting “circled with diamonds” implies that only one ring is owned.
More than one item:
Omitting the commas implies that the author has written more than one article and that more than one ring is owned, and you are referring to one specific article or the ring with diamonds circling it.