I have done the Pick-A-Pearl every trip since 2009. I have a few pendants and a couple of pairs of earrings.
Last trip, my sister did Pick-A-Pearl, but really for me as a gift for planning our trip. She wanted to get me earrings, but picked a single 6.75 pearl. They pulled out a couple of loose pearls and allowed her to buy a close match for the same price as opening another oyster so we'd have a matched pair for earrings. (I chose silver studs with petals at the stems. Very pretty.)
Anyhow, I'm mentioning this because on previous trips, they told us you had to get "twins" inside your oyster to get a pair for earrings. I did get twin golden pearls in 2010 and had those drilled with plain gold stems for studs.
But in 2016, they were willing to sell you a match if you were looking for a pair of pearls so if it's a pair you want for earrings, it's doable without finding twins.