There was a body called Senate of Russian Empire. Within it there was a Department of Geroldia ( Департамент Герольдии). Poles and Lithuanians adressed copies of burth rates and documents on property in past to confirm nobility. You may learn mani details from that documents.
where are these documents now ? :)
First consult Seweryn Uruski if your surnames are before letter R
what about choromanski ? I seen something in the St Petersburg website
on Choromanski but it was spelled horomanski I think