Beautifully Shaped Stone (Tool?) with Incised 1843 antique whirligig but this couple struck me

but this couple struck me as especially striking

Shipped in a hard protective case

possibly repaired

no chips or other issues

Small cross pins: 5/8" d

Beautifully Shaped Stone (Tool?) with Incised 1843 antique whirligig but this couple struck meI really don't know if this stone served a function, though I have to think that it did it has too long and smooth of a bottom edge, and fits too perfect in one's grip not to have been used for something! And one has to imagine that the J. D who took the time to carefully caved his initials and the year 1843 into it did so because it was an important thing to him. I am sure someone out there can identify the use my grabbing it (and not letting it go)