The National Monument Record, available via Coflein, describes Graeanog Standing Stone thus:
An erect monolith, 3.05m high by 0.9m by 0.68m, set 7.0m SE of a kerbed cairn (Nprn93558), with a second cairn (Nprn93559), c.35m SSW.
The eight figure grid reference given for the stone is SH45524917 and the National Primary Record Number (NPRN) is 93557.
It’s worth noting that there’s a duplicate record for this site (NPRN: 302389) listed on Coflein. In other words what appears to be two standing stones is in fact one.