Cork is a natural product. It is actually the bark of a certain tree. Most (maybe all) of the cork used in the rod making industry comes from the country of Portugal in Europe. The folks over there who raise the cork are very careful about how & when they harvest it. They need to make sure they don't take too much cork off the tree, or too soon.
The cork that rod makers use typically comes in rings. These rings are usually 1 1/4" round in diameter & are either 1/2" thick (the most common) or 1/4" thick. The rod maker determines how many rings are needed to make the grip they're working on & then - if they don't already have a center hole - bores a hole in the middle of each ring. These rings are then glued together into a cylinder shape, as long as the grip will be. Once the glue sets up, the cork is spun - usually on a lathe - & sanded down to the desired size & shape.
As I said, cork is a natural product. No two pieces are exactly the same & each will have at least a few imperfections. That's to be expected. The rod maker simply works around these imperfections by placing the rings so that the grip will be the best it can be. A cork grip is most vulnerable to damage at the ends, front & back. A conscientious rod maker will be sure there are very few pits in those areas of the grip.
To me this trend of using "perfect" cork made no sense at all. Cork is supposed to have little imperfections here & there in my opinion. Like bamboo, it is a natural product. These grips made with flawless cork always looked fake, or somehow unnatural to me. As the price of cork goes up it is becoming one of the most expensive components on the rod. To me it gets a little ridiculous to be paying $3.50 or more per 1/2" ring of cork (not counting the costs of the glue, the tools, & the labor to turn it into a finished grip)- especially if that perfect cork looks strange (in my eyes).
Using totally flawless cork never made sense to me from an angling perspective either. I mean, you're going to be paying a lot extra for that very rare cork on your rod. Wonderful, if that's what you want but have you considered how it will look in a little while? Cork will, for lack of a better term, 'patina' with use. It will change color from holding it in your hand as it absorbs & takes on the dirt & grime on your hands. Your fishing, not sitting down to dinner, so your hands aren't always their cleanest when you're along the stream. The cork will darken as time goes on. True, you can make the cork look new again if you clean it. Most anglers, I suspect, don't clean their rod grips with soap & water after every outing though. So how long will it be before you "perfect" cork grip is no longer perfect?