Also known as the 6 pieces of everyday jewelry because they can be worn any and everywhere. Here they are:
Diamond wedding band
Diamond stud earrings
Diamond solitaire pendant
Strand of pearls
All these items should be in every woman’s wardrobe and can be worn everyday. For example, those diamond stud earrings can be worn with jeans to the grocery store or with that little black dress to a special night out, and in both cases you are not either overdressed or under dressed for the occasion.
The same thing applies for all the items on the list.
So when wondering what to get the love of your life, any of those Essential pieces will be the most worn item of jewelry she owns. These things are also thought of as “everyday” jewelry. If she doesn't own a necklace you see her wear a lot, if not everyday, then a diamond solitaire pendant is perfect.