Pokemon Sword and Shield add an unusual ghost Pokemon named Sinistea. While it isn’t exactly obvious, this creature has two different forms. The chipped form is the rare of the two and generally more desirable. But, the stamp showing which one you have only appears on the underside of the Pokemon, on the inner part of the base of the teacup, so you can’t see which one you have. Fortunately, it isn’t too difficult to appraise a Sinistea.
You can discover which one you have once you have acquired a Chipped Pot or Cracked Pot. These are the Sinistea evolutionary items. A free Cracked Pot is available in Stow-on-Side if you climb the ladder next to the stairway on the way to that town’s gym. But, if you want Chipped Pots or more Cracked Pots, you have to wait for the street vendor in that village to offer one as his bargain of the day.
Though, if you have only just started catching them, you could use your Pokedex to determine if you have even seen a Chipped Sinistea yet. It won’t offer the option to see the other form until you have encountered one.
Once you either pot, you can use it to appraise your Sinistea. When you go to your bag and select the item, you can see if it is or isn’t compatible with the Pokemon you have. This tells you right away if the characters is Chipped or Cracked.