Beautiful badge, still I'm not sure it's GWL, even having in mind the set up. This one looks like the first (for official awarding) type of Bugstern made by Meybauer. The other known variants (with screw back) were made later for commercial sales. I'll try to make translation later and post an article about it from Baltic Cross book.
Taken from upcoming K. Nikolayev book Baltic Cross and other Freikorps awards in Baltics 1918-19:
On the 1st of February the General Headquarters of Schutztruppe Bug established the Commemorative Badge. It was awarded to every volunteer for one month service in Schutztruppe, starting from 26.03 1919 it also applied to Freikorps Olita members.
According to correspondence between Klietmann and Kobe von Koppenfels ( the commander), the badge was designed by Keppenfels himself.
An order was placed to Militar-Effekten und Orden-Fabrik Paul Meybauer, Berlin, which produced several different variants of the badge:
1. Badge made of silvered non-ferrous metal. The central part (medallion) is coloured with dark-blue lacquer, with needle set up.
According to Kobe von Koppenfels this was the only version used for official awarding in the very beginning.
As stated in correspondence between Klietmann and Hans Meybauer dated 1938, the company produced 2 more badge modifications for commercial sales to Schutztruppe volunteers:
2. Badge made of silvered non-ferrous metals . The central part (medallion) is covered with violet enamel, the wreath is covered with light-green, with needle set-up.
3. A counterpart badge made of 800, 900 and (rarely) 925 Silver . The central part is covered with violet enamel, the wreath is enameled with light-green. This one came with both needle and screw-back set up.
As stated by Hans Meybauer, the company produced total of 6500 examples of Bugstern badge.
The badge shown in this thread is the 1st modification, made for official awarding.
As you see, the discussion between Meybauer and Klietmann is dated as late as 1938, and till this time no other companies were involved into the production of these badges, only Meybauer exclusively.
Here comes the one from an author of the article, Mr. Nikolayev, a silver badge with unique needle set up, these are usually met with screw back. So far the only known example...hope we can see more coming!