everyday diamonds

I am always curious to know what one piece of jewelry someone would invest in if they had to choose.  Instinctually, I would say I would invest in a good ring above all else yet those are the pieces of jewelry I swap out the most from day to day.  Lately, I have been wearing the same earrings, necklace and bracelets every day... so wouldn't I want to invest in really good pieces of those instead since I would be getting more out of my dollar per wear?!  Still I would rather spend my money on a really spectacular ring.  So I'm curious readers... which piece of jewelry would you choose to invest in?  A ring that could work for everyday?  A great pair of earrings that works with everything you wear?  A necklace that makes you feel fantastic every time you wear it?  A bracelet that goes with all of your other jewelry effortlessly?  (Images from here, here, here, and here.  P.S. How unbelievable are those Asscher cut diamond studs?!  I am DYING over them!)