Swatches from a triad of Irodori Antique watercolors from Holbein.
Left: Swatches made in 2006 in an Aquabee spiral sketchbook. (That's a pink Post-it Note at the bottom right that I forgot to remove before scanning.)
I was talking about using limited color palettes in watercolor a week or so ago (actually I'm always talking and writing about this) and someone asked for recommendations if only three tubes of gouache paint were to be purchased. I can't find that note and the person's name, or where I addressed it in the comments, but what I can say is that when I shut down the computer that night I got out an old sketchbook to check on something and I found this yummy chart of a test of three Irodori Antique Watercolor paints from Holbein.
Whoa—I'm not suggesting you run out and buy these paints. I'm posting this chart as an example of one of the many experiments you need to do when you are testing out new paints and trying to ascertain where they will fit in your palette (if at all).
Before you buy this or any brand please make sure that the pigments used in the paint meet whatever standards you have for lightfast properties and other component characteristics.
If you paint transparent watercolors you'll find that the three colors selected here will all be too heavy for most of your applications. Also these paints don't rewet well at all (there are warnings about only putting out what you need for a session in every sales brochure on them) so they aren't a useful candidate for making your own pans of color. But if you like to play with different textures in your watercolors or work in the studio or field from tubed paint you might want to look at the Irodori Antique Watercolor line from Holbein. (The colors in the line are colors used in "ancient" Japanese and Chinese art, hence the use of the word "antique" in their name.)
Regardless of what brand of paints you're using you need to take some time to explore the blending possibilities and see what you really can do with simply 3 paints—in this case a red, blue, and yellow. I would be quite happy working with this lot in the studio as I can get my Malamute Gray.