Is there a continuation of Darker than Black: Gemini of the Meteor?
According to both Wikipedia and MyAnimeList, there has not been any sequel produced to Darker than Black: Ryuusei no Gemini. There is a 4 episode OVA prequel, produced after Gemini, Darker than Black: Kuro no Keiyakusha Gaiden, which fills in the gap between the first and second season.

There is also no continuation in any other form. Darker than Black was originally produced as an anime. There was a short manga adaptation, but it really only adapted the first season of the anime. There was, however, an original manga
continuation of that manga series, titled Darker than Black: Shikkoku no Hana. It is not an adaptation of Ryuusei no Gemini, but replaces Gemini completely.

To the best of my knowledge, there have not been any further announcements of other continuations of the franchise, and the most recent activity was over 2 years ago. It's certainly still possible that they intend to produce another series, but there is no news confirming any such intentions so it seems unlikely.