Can't install RMagick 2.13.1. Can't find MagickWand.h.

If you're on Ubuntu, installing this package is what fixed it for me:

sudo apt-get install libmagickwand-dev

It looks like ImageMagick 7 changed include file path.

On building rmagick, since it includes file as wand/MagickWand.h There are no workarounds. It looks like sticking with ImageMagick 6 for now.

On Mac OS X (I tested on Sierra), I used HomeBrew's versions tap like:

brew tap homebrew/versions
brew install imagemagick@6

Then, use the path shown on above installation:

PKG_CONFIG_PATH=/usr/local/opt/imagemagick@6/lib/pkgconfig gem install rmagick

To install with ImageMagick 6.

I didn't want to mess with environment variables since I wanted bundler to be able to compile this gem on its own on a CI machine. Instead, I used Homebrew to install pkg-config:

brew install pkgconfig

and the next time I tried compiling the RMagick gem it found the header file without issue.

(This is pkg-config 0.28, ImageMagick 6.8.0-10, and RMagick 2.13.2, all on Mountain Lion.)