Rohrer & Klingner Alt-Goldgrün Ink

One of Rohrer & Klingner's most popular fountain pen inks, Alt-Goldgrün (essentially "Old-style Golden Green") is a beautiful, nostalgic ink that reminds me of the turn of the (19th/20th) century. It's something you might see in a Gustav Klimt painting or the colors you might find in other Jugendstil (art nouveau) pieces.

Or maybe it's just a nice golden-green color. (Can you tell that I grew up in Austria?)

This is dye-based (non-waterproof) ink, made in Germany.