Final answer:
A diamond ring that is shoplifted from a store display is considered the subject of Theft.
Step-by-step explanation:
The subject of a diamond ring shoplifted from a store display is Theft.
Theft refers to the act of taking someone else's property without their permission and with the intent to permanently deprive them of it. In this case, the diamond ring is stolen from a store display, which is considered theft.
Theft is a crime in which the perpetrator unlawfully takes someone else's property. It does not involve the use of force or threats, which distinguishes it from Robbery.