Preheat a cast iron skillet over medium high heat.
In the meantime, pat the scallops very dry with a paper towel. Sprinkle the sea scallops with salt and pepper, to season.
When the pan is hot, add the grapeseed oil, then drop in your scallops, giving them enough room in between so they don’t steam each other. The scallops should make a sizzling noise when you put them in the pan.
Cook the scallops for 2 minutes, making sure not to move them or touch them at all.
Flip the scallops over with a pair of tongs, and add the butter to the pan. Let the scallops cook for 1 more minute, basting the scallops with the butter.