They are frequently pale yellow or light gray in color.
Usually you put the eyestone under the eyelid at the inner canthus of the eye, and the automatic action of the eye moves it slowly over the eyeball; thus it is likely to carry along with it any foreign body that has accidentally lodged in the eye.

When the stone has reached the outer canthus you can remove it, along with any foreign substance it may have collected on its journey over the eye.
Halstead's sufferings had aroused my sympathy, and I set off at top speed; by running wherever the road was not uphill, I reached Lurvey's Mills in considerably less than an hour.

Several mill hands were piling logs by the stream bank, and I stopped to inquire for Prudent Bedell.
Resting on their peavies, the men glanced at me curiously.
"D'ye mean the old sin-smeller ?" one of them asked me.

"What is it you want ?" "I want to borrow his eyestone," I replied.
"Well," the man said, "he lives just across the bridge yonder, in that little green house." It was a veritable bandbox of a house, boarded, battened, and painted bright green; the door was a vivid yellow.

In response to my knock, a short, elderly man opened the door.