‘Jun Sei Honyama’ old stock natural stone, aneasy to use hard fine finisher, always nice to find. The stone is a bit wedge shape and will need to be flattened a bit more on the bottom and set on a dai, otherwise a good stone. Price adjusted for wedge shape
Marked only Jun Sei Honyama (genuine Honyama) these koppa (small, off sized or irrregular stones) are old stock stones from an old established stone dealer in Kyoto. The mark is somewhat vague, no mine or strata but they are excellent stones, priced low for their lack of specific ID and smaller size, not for their performance, they sharpen way better than what their price tag might suggest.
Being koppa there are roughly cut and do not have a polished face or lacquered sides, measurements are from the widest dimensions. These are priced to take into account any small imperfections, any significant flaws will be listed. these are excellent performers on par but not premium stones.