Earrings at Level 50

[Orophin]

Sure, the red coral earrings are nice, but they only have the one materia slot. You're either tying for CP or getting a small bonus to your Control or Craftsmanship.

You can overmeld every item with a materia slot with up to 5 materia, so you can add more craftmanship and control.

[Norbi]

In order to get the Crimson Standard earrings, you need to do 5000 Supply Missions for the Maelstrom. You can do one supply mission per day per crafting class. That means 8 supply missions per day. That means 625 days minimum.

Or you can get Red Coral Earrings immediately for a couple thousand gil.

Also:

You can overmeld every item with a materia slot with up to 5 materia, so you can add more craftmanship and control.

^ This.

You can fit 3 Craftsmanship + 3 Control + 6 CP into Red Coral Earrings, and if they're HQ they come with 28 CP already. So that's 34CP, 3 Craftsmanship and 3 Control (HQ Red Coral Earrings with materia) for only a little effort spent in over-melding, vs. 32 CP, 0 Craftsmanship and 0 Control (Crimson Standard Earrings) for almost 2 years of consistent item turn-ins.