Thanks Roy, that's better.
Confusing stuff follows, hope I can get it across: Most people would claim the manufacturer was the company of "Ernst Bohne & Soehne" (Ernst Bohne & Sons) from the town of Rudolstadt (today Rudolstadt-Volkstedt) in Thuringia; they sold out to the Heubach brothers in 1919.
Just for the books: many smaller (non-German) reference books and many websites don't show this mark under that company header at all, but in fact the mark was registered by Bohne at the R.W.Z.R. [abbr. for "Reichswarenzeichenregister", the central (trade)mark registration office] on February 15th 1909 under file number #114 951. The Roentgen book of marks (2007 edition) for example does not show all this, the 1992 edition of Danckert at least drops a few hints.
Anyway, most sources say that the mark was used until 1937; the period between 1919 and 1937 of course saw the rights used by the Bohne successor at that time, the Heubach brothers.
After the takeover through Albert Stahl & Co in 1937 the whole stuff went into hibernation until after the war. And then (you probably guessed it) the new owner started re-using old molds and marks.
So in *many* cases the mark that originally belonged to Ernst Bohne was actually re-used on newer Albert Stahl items. Finding out which period your item comes from would require a hands-on check by somebody who has experience in dating items.
If you yourself have a little experience, you can check yourself: when the gilding is still near perfect and the glaze only has minimal amounts of polishing-scratches (some call it scuffing) from cleaning it's near 99% sure to be the post-1950 version.
Oh and if somebody comes up with some codswallop regarding country-of-origin marks expecially after the war and such ... just ignore it. I could also add a rundown here but that is really a different (and lengthy) matter