I'll dive right into this subject. How we hold our rings (engagement rings, wedding rings,...) while wearing and taking it off affects how clean our diamonds stay and how dirty and dull looking they get.
The molecular structure of diamonds make them a sticky stone. Oils from the finger tips easily adhere to the surface of diamonds and leave a fingerprint. Overtime, these fingerprints build up causing the diamonds to look dull.
When wearing and taking off your ring, hold it from the sides where there is more metal and less or no stones and wiggle the ring on. When taking the ring off, hold it from the sides, on the metal, and wiggle it off. It takes longer to take off a ring when you hold it from the sides. That extra few seconds is well worth the time.
Another important reason to hold your ring from the metal is because pressure from the fingers, while wearing and taking it off, may contribute to stones getting loose over time.